Tamil Tiger guerrillas, facing a military onslaught in Sri Lanka's north, have let loose suicide bombers in the guise of beggars and pregnant women in Colombo, a media report said Friday.

The warning has come from the police intelligence, the state-run Daily News reported.

It said the police had arrested a leading intelligence operative of the Liberation Tigers of Tamil Eelam (LTTE) at Kiribathgoda, a commercial town about 15 km north of Colombo. He was dressed like a beggar.