Sri Lanka police had also warned of attacks on Indian high commission

Sri Lanka's police chief made a nationwide alert 10 days before Sunday's bomb attacks in the country that suicide bombers planned to hit "prominent churches", according to the warning seen by AFP.

Police chief Pujuth Jayasundara sent an intelligence warning to top officers on April 11 setting out the threat.

"A foreign intelligence agency has reported that the NTJ (National Thowheeth Jama'ath) is planning to carry out suicide attacks targeting prominent churches as well as the Indian high commission in Colombo," said the alert.

The NTJ is a radical Muslim group in Sri Lanka that came to notice last year when it was linked to the vandalization of Buddhist statues.

At least 129 people were killed in six bomb attacks Sunday that included three churches. AFP