Sri Lankan soldiers are in a gun battle with suspects linked to the Easter attacks in Eastern Province, a military spokesman has said.
The development came as religious leaders cancelled public prayer gatherings in the South Asian country amid warnings of more attacks, along with retaliatory sectarian violence.
Across the capital Colombo, there was a visible increase of security as authorities warned of another attack and pursued suspects that could have access to explosives.
And in an unusually specific warning, the US Embassy in Sri Lanka said places of worship could be hit by extremists this weekend.
More than 250 people were killed in a wave of bombings at churches and hotels on Easter Sunday, with at least eight Britons among the dead.
It came after the country’s president this week shook up the country’s top security establishment after officials failed to act on intelligence reports warning of possible attacks before the bombings.
On Thursday, the British Foreign Office advised against all but essential travel to Sri Lanka.