A rift between Sri Lanka's president and prime minister that sparked a crisis last year came under scrutiny on Monday a day after a series of deadly bomb blasts, with questions over how the government handled a recent warning of an attack.

The prime minister has been kept out of intelligence briefings since he fell out with the president, a government minister said, a day after Easter attacks on churches and hotels killed 290 people and wounded nearly 500.

Police had been warned this month about a possible attack on churches by a little-known domestic Islamist group, according to a document seen by Reuters.