An improvised pipe bomb discovered close to Colombo's main airport was successfully defused by the Sri Lanka air force, police said.

A police source told AFP that a "homemade" pipe bomb had been found late Sunday on a road leading towards the main terminal, which remains open with heavy security after deadly attacks on churchs and hotels.

Airforce spokesperson Group Captain Gihan Seneviratne said the IED was believed to be locally manufactured.

A string of eight powerful blasts, including suicide attacks, struck churches and luxury hotels frequented by foreigners in Sri Lanka on Easter Sunday, killing 215 people, including three Indians, and shattering a decade of peace in the island nation since the end of the brutal civil war with the LTTE.

The blasts - one of the deadliest attacks in the country's history - targeted St Anthony's Church in Colombo, St Sebastian's Church in the western coastal town of Negombo and Zion Church in the eastern town of Batticaloa around 8.45 a.m. (local time) as the Easter Sunday mass were in progress, police spokesman Ruwan Gunasekera said.