A blast hit near a church in Sri Lanka's capital on Monday as police tried to defuse a new bomb found by the site, a police spokesman said.
There was no immediate information on injuries in the blast, or how large it was. The explosion happened around 50 metres from the St Anthony's Shrine, one of three churches targeted in a string of suicide bombs on Sunday that killed nearly 300 people.
The death toll from Sunday's attacks rose dramatically Monday to 290 - including dozens of foreigners - in the worst atrocity since the country's civil war ended a decade ago.
More than 500 people were injured in the assault that saw suicide bombers hit three high-end hotels popular with foreign tourists, and three churches, unleashing carnage in Colombo and beyond.