Colombo: Sri Lanka's Catholic church will telecast a mass every week after cancelling regular services over fears of a repeat of the Easter Sunday suicide bombings that killed at least 257 people.

Father Edmund Tillakaratne said that public masses were suspended for a second week, but a service conducted by cardinal Malcolm Ranjith will be broadcast on national television.

"It will be like last Sunday when we had a service at Archbishop's chapel and telecast it live," Tillakaratne said.

Ranjith, who is also archbishop of Colombo, said that a "reliable foreign source" had alerted him to possible attacks this weekend, leading him to cancel Sunday services for the second week.

"The information we have from a reliable foreign source is that attackers are planning to hit a very famous church and a Catholic institution," the cardinal said in a statement.

Official sources said the Thewatte National Basilica, just outside Colombo, was the suspected target, and the military deployed hundreds of troops to search the area.

"There were no explosives found, but we have stepped up security in the neighbourhood," a police official said.

The government is going ahead with plans to reopen public schools on Monday, but the Church said Catholic schools will remain shut "until further notice".

Sri Lankan authorities had advance warnings from Indian intelligence prior to the Easter attacks but police and security forces failed to act on it, leading to Sri Lanka's worst single suicide attack against civilians.

There were at least 42 foreigners among the 257 that were killed while about 480 others were left wounded in the attacks targeting three churches and three luxury hotels on April 21.

Armed guards have been stationed outside hotels, churches, Buddhist temples and mosques across the country since the attacks.

Prime Minister Ranil Wickremesinghe said that some of the conspirators may still be at large.

"Most of those responsible for the Easter attacks have been arrested. Some have been killed," Wickremesinghe said during a tour of the island's east, where a Christian church was hit. “We are trying to see if there are any more secret IS cells in the country," he said adding, "We will ensure that IS terrorism will be eradicated from our land."

Sri Lanka bolstered security Friday with fears of attacks against several bridges and flyovers in Colombo as well as police stations.

He hoped normalcy would return by Monday when public schools reopen after an extended Easter vacation. About 50 children were among those killed.

The attacks were blamed on a splinter group of the local National Thowheeth Jama'ath whose leader was among the suicide bombers. The group had pledged an oath of allegiance to the Islamic State group.