Mr Wickremesinghe acknowledged on Sunday that the government had some prior information about possible attacks on churches involving a little-known Islamist group but said ministers had not been told.
The explosion at the house in the Colombo suburb occurred when security forces raided a house there on Sunday afternoon, several hours after the attack.
Health Minister Rajitha Senaratne said all of the suicide bombers were Sri Lankan citizens from a domestic Muslim militant group named National Thowfeek Jamaath, but that authorities suspect foreign links. The country's small Christian community has seen only scattered incidents of harassment in recent years. To curb that feeling, he's helping organize a prayer event planned this weekend at the Sarana International Buddhist Center, a Tukwila temple that serves as a popular gathering spot for the Sri Lankan community.
Government officials said Sunday that they were recently warned by a foreign government that the National Thowheed Jamath posed an imminent threat but failed to take the appropriate precautions.
"The intelligence reports [indicate] that foreign terrorist organisations are behind the local terrorists".
He added, "I just don't believe this was a locally-conducted attack".
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The mother, who was 32 at the time, was hugging her son to protect him as a school bus ploughed into their vehicle . They were sat in the back seat when the bus hit the auto and Ms Abdullah threw herself protectively around him.
The United States pledged support for the investigation, dispatching FBI agents to help.
290 people have been killed and over 500 have been injured in the eight explosions.
Two government ministers have also alluded to intelligence failures.
Major questions are now being asked over whether Sri Lankan police did enough to head off fears of suicide attacks on churches.
Lalitha weeps on the coffin with the remains of 12-year old niece, Sneha Savindi, who was a victim of the Easter Sunday bombing at St. Sebastian Church in Negombo, Sri Lanka, April 22, 2019.
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The AirAsia spokesperson apologised for any inconvenience caused by the delay and said the airline would assist guests in re-booking.
All the attacks were carried out by suicide bombers, officials said.
"India has frequently been sharing inputs about radicalization activities with Sri Lankan counterparts as certain elements suspected to be linked with the island nation's little known outfit have come under the security scanner in the past", said a source in the Intelligence Bureau. Trump pledged USA support in bringing the perpetrators to justice, and the leaders reaffirmed their commitment to the fight against global terrorism, a pool report said.
A statement from President Maithripala Sirisena's office said he would be seeking information on who was responsible for plotting the attacks.
President Sirisena also said the nation will be under an emergency from the midnight of Monday.
The government announced on Monday that it is gazetting some of the clauses of the Prevention of Terrorism Act to tighten the law and order system. However, the group's visibility increased in 2018, after its members were accused of vandalizing a number of Buddhist statues in the country.
"National Thowheed Jamath was involved". Governor of The Eastern Province, Mahamood Lebbe Alim Mohamed Hizbullah, also said on Sunday NTJ had no role in the attacks.
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Clair Secondary School and the Sarnia Saints program, scored a try in a 24-12 win over the U-S in the semifinals. Landry and Paquin, in her first sevens event since the Rio Olympics, were named to the tournament Dream Team.