15 people were killed in clashes overnight between special units of the Sri Lankan security forces and suspected members of the Tawhid National Group - believed to be linked to recent attacks - in the Kalmonai region on Sri Lanka's east coast.
AFP reported that three men blew themselves up during an attempt to storm the police and military to a site believed to be a hideout of the Islamic State Organization in Kalmonai east of the country, killing three women and six children.
"Three other men, also suspected of suicide, were found outside the house," the police said, adding that a civilian was killed in the exchange of fire.
The joint police-army operation was carried out following a report that those responsible for the Easter attacks, which killed more than 250 people, were holed up in an area in Kalmonai, 370 km east of the capital.
Police said Friday they had raided a house in the nearby town of Samanthurai, and found explosives, lightning and flags bearing the symbols of state organization.
In a separate incident, police arrested three people in Colombo with a kilogram of C-4 explosive.
The authorities also announced yesterday that Zahran Hashem, leader of the Jamaat-e-Islamiya (JI) accused of being behind the attacks - which has been being searched all over the country for five days - was killed in one of the "suicide" attacks.
"We have information now that there are about 140 people linked to the organization of the Islamic state, we are able to eliminate them all, and this is what we are going to do," President Mathirepala Sericina said.
Tension remains high in the country as suspects continue to be prosecuted. Security forces have arrested about 75 people since Sunday in connection with the attacks.
On Friday, the State Department raised the level of travel warning to Sri Lanka, urging its citizens to review their travel plans to the island following a series of attacks.
The United Kingdom, Israel, the Netherlands and other countries have requested that they avoid going to Sri Lanka and leaving the country.