Colombo, Apr 24 (IANS): Sri Lanka's President Maithripala Sirisena said on Tuesday that he would move quickly to restructure country's intelligence and security apparatus in response to a failure to act on warnings received ahead of the Easter Sunday attacks, which left more than 300 people dead.

"I will completely restructure the police and security forces in the coming weeks. I expect to change the heads of defence establishments within next 24 hours," Sirisena said in a televised speech, the Efe news reported.

"People question why action had not been taken despite the availability of intelligence support from a friendly neighbouring country (India)," the President said.

"The security officials who got the intelligence report did not share it with me. Appropriate actions would have been taken," he said.

"I have decided to take stern action against these officials," he said.

The attacks began at 8.45 a.m. Sunday with six coordinated explosions at three luxury hotels in Colombo and three churches across the country as they were holding Easter services.

Another blast in the afternoon left two dead in a small hotel near Dehiwala Zoo, around 10km south of the capital.

The eighth explosion killed three police officers at a residential complex in Dematagoda.

Most of the attacks were carried out by suicide bombers.

The death toll stands at 321, while 521 others were wounded.

The Islamic State said Tuesday via its Amaq news outlet that it was responsible for the attack, but without offering any evidence. The terror group has made a series of false claims in recent years.

Later, however, Amaq disseminated a video purporting to show the Sri Lankan perpetrators swearing loyalty to IS and its leader, Abu Bakr al-Bagdadi.

The footage features eight people standing in front of a black IS banner. Seven of the figures are masked, while the eighth, whose face is visible, administers the oath in Arabic.