The Islamic State has reportedly claimed responsibility for the attacks.

"That is quite possible, given the telephone calls that they were making and the fact that some of them have received training abroad and the fact that IS leaders have made statements admitting the links to Sri Lanka. That is something we can assume," Sirisena told Sky News media outlet when asked whether he thought that the bombings were masterminded by a foreign organization and not a local Sri Lankan one.

The president added that IS may have launched a new strategy to target smaller countries, since losing their caliphate in late March after being defeated on the ground in Syria.

Sirisena also said that Sri Lankan authorities had been aware of a small group of the country's citizens who had traveled abroad to receive IS training over the past decade.

On Wednesday, Sky News released information about the eight identified men who were involved in the suicide bombing attacks in Colombo and other cities throughout the Southeast Asian country. According to the media outlet, CCTV footage from the day of the attacks showed that the men were highly coordinated in their actions. It also said that all of the men were Sri Lankan and were well-educated and well-traveled.

The Easter Sunday bombings devastated the nation and left the world in shock. In the week since the event, Sri Lankan authorities have made over 100 arrests in connection with the bombings and warned the nation on Tuesday that IS militants were currently planning more attacks.