The coordinated Easter Sunday bombings that ripped through Sri Lankan churches and luxury hotels were carried out by seven suicide bombers.
The death toll after the terrorist attacks in Sri Lanka is now 290, with an estimated 500 people wounded.
An analysis of the attackers' body parts made clear that they were suicide bombers, said Ariyananda Welianga, a forensic crime investigator. He said most attacks were by one bomber, with two at Colombo's Shangri-La Hotel.
Meanwhile, Sri Lankan police investigating the bombings are examining reports that intelligence agencies had warnings of possible attacks, officials said Monday.
Prime Minister Ranil Wickremesinghe acknowledged the Government had "prior information" of attacks on churches involving a little-known local Islamist group but didn't do enough about it.
Telecommunications Minister Harin Fernando tweeted, "Some intelligence officers were aware of this incidence. Therefore there was a delay in action. Serious action needs to be taken as to why this warning was ignored." He said his father had heard of the possibility of an attack as well and had warned him not to enter popular churches.
The police's Criminal Investigation Department, which is handling the investigation into the blasts, will look into those reports, Gunasekara said.
Earlier, Defence Minister Ruwan Wijewardena described the bombings as a terrorist attack by religious extremists, and police said 13 suspects were arrested, though there was no immediate claim of responsibility. Wijewardena said most of the blasts were believed to have been suicide attacks.
The explosions at three churches and three hotels - most of them in or around Colombo, the capital - collapsed ceilings and blew out windows, killing worshippers and hotel guests in one scene after another of smoke, blood, broken glass, screams and wailing alarms. Victims were carried out of blood-spattered pews.
"People were being dragged out," said Bhanuka Harischandra, of Colombo, a 24-year-old founder of a tech marketing company who was going to the city's Shangri-La Hotel for a meeting when it was bombed. "People didn't know what was going on. It was panic mode."
He added, "There was blood everywhere."
Most of those killed were Sri Lankans. But the three hotels and one of the churches, St. Anthony's Shrine, are frequented by foreign tourists, and Sri Lankan officials said the bodies of at least 32 foreigners from a variety of countries were recovered.
Three Indians, three Danes, five Britons, "several" US citizens and a Dutch national were killed, their governments said.
Sri Lanka's Tourism Board also said nationals from China, Belgium, Japan, Turkey, Bangladesh, Pakistan and Portugal were killed.
Wickremesinghe said he feared the massacre could trigger instability in Sri Lanka, a country of about 21 million people, and vowed to "vest all necessary powers with the defence forces" to take action against those responsible.
The government imposed a nationwide curfew from 6pm to 6am and blocked Facebook and other social media, saying it needed to curtail the spread of false information and ease tension.
French news agency Agence France Presse reported it had seen documents showing Sri Lanka's police chief Pujuth Jayasundara issued an intelligence alert to top officers 10 days ago, warning that suicide bombers planned to hit "prominent churches". He cited a foreign intelligence service as reporting that a little- known Islamist group was involved.
Wickremsinghe called for an inquiry into how the information was used, and also said the government needs to look at the international links of a local militant group.
Prime Minister Jacinda Ardern has extended New Zealand's condolences to the government and people of Sri Lanka following the Easter Sunday bombings.
"New Zealand condemns all acts of terrorism, and our resolve has only been strengthened by the attack on our soil on the 15th of March.
To see an attack in Sri Lanka while people were in churches and at hotels is devastating," Ardern said.
"New Zealand rejects all forms of extremism and stands for freedom of religion and the right to worship safely.
Collectively we must find the will and the answers to end such violence."
HISTORY OF BLOODSHED
The scale of the bloodshed recalled the worst days of Sri Lanka's 26-year civil war, in which the Tamil Tigers, a rebel group from the ethnic Tamil minority, sought independence from the Buddhist-majority country. During the war, the Tigers and other rebels carried out a multitude of bombings. The Tamils are Hindu, Muslim and Christian.
Sri Lanka, situated off the southern tip of India, is about 70 per cent Buddhist, with the rest of the population Muslim, Hindu or Christian. While there have been scattered incidents of anti-Christian harassment in recent years, there has been nothing on the scale of what happened on Sunday.
There is also no history of violent Muslim militants in Sri Lanka. However, tensions have been running high more recently between hard-line Buddhist monks and Muslims.
Two Muslim groups in Sri Lanka condemned the church attacks, as did countries around the world, and Pope Francis expressed condolences at the end of his traditional Easter Sunday blessing in Rome.
"I want to express my loving closeness to the Christian community, targeted while they were gathered in prayer, and all the victims of such cruel violence," Francis said.
Six nearly simultaneous blasts took place in the morning in Colombo at St. Anthony's Shrine - a Catholic church - and the Cinnamon Grand, Shangri-La and Kingsbury hotels. After a lull of a few hours, two more explosions occurred at St. Sebastian Catholic church in Negombo, a mostly Catholic town 37 kilometres north of Colombo, and at the Protestant Zion church in the town of Batticaloa, about 1300km to the east.
Three police officers were killed while conducting a search at a suspected safe house in Dematagoda, on the outskirts of Colombo, when its occupants apparently detonated explosives to prevent arrest, Wijewardena said.
An improvised explosive device was found inside a plastic pipe close to Bandaranaike International Airport in Colombo and defused, a spokesman for the Air Force said.
Local TV showed the Shangri-La's second-floor restaurant was gutted, with the ceiling and windows blown out. Loose wires hung and tables were overturned in the blackened space. From outside the police cordon, three bodies could be seen covered in white sheets.
Foreign tourists hurriedly took to their cellphones to text family and loved ones around the world that they were OK.
One group was on a 15-day tour of the tropical island country, seeing such sites as Buddhist monuments, tea plantations, jungle eco-lodges and sandy beaches. The tour started last week in Negombo, where one of the blasts took place, and was supposed to end in Colombo, but that may be dropped from the itinerary.
"Having experienced the open and welcoming Sri Lanka during my last week travelling through the country, I had a sense that the country was turning the corner, and in particular those in the tourism industry were hopeful for the future," said Peter Kelson, a technology manager from Sydney.
"Apart from the tragedy of the immediate victims of the bombings, I worry that these terrible events will set the country back significantly," he said.
Tour group leader Suminda Dodangoda was exasperated at the political problems still convulsing his country.
"We are still at war" more than three decades later, he told the tourists.
Sri Lankan forces defeated the Tamil Tiger rebels in 2009, ending a civil war that took over 100,000 lives, with both sides accused of grave human rights violations.
Harischandra, who witnessed the attack at the Shangri-La Hotel, said there was "a lot of tension" after the bombings, but added: "We've been through these kinds of situations before."
He said Sri Lankans are "an amazing bunch" and noted that his social media feed was flooded with photos of people standing in long lines to give blood.
In a sign that the attacks could lead to communal violence, police reported on Sunday night there had been a petrol bomb attack on a mosque in the northwestern district of Puttalum and arson attacks on two shops owned by Muslims in the western district of Kalutara.
MFAT RESPONDS TO BOMB BLASTS
The Ministry of Foreign Affairs and Trade is responding to the bombings.
A Mfat spokesperson said New Zealanders in Sri Lanka should be vigilant in public areas and follow any advice issued by local authorities.
New Zealanders in Sri Lanka in need of consular assistance should contact the New Zealand High Commission in New Delhi, on +91 11 468 83170.
There are currently 115 New Zealanders registered as being in Sri Lanka.
- AP, Stuff and agencies