Manickathasan, the military-wing leader of PLOTE, and his deputy K Ilanko were killed in a claymore mine attack at his office in Vavuniya, 254 km north of Colombo.

Tamil rebels have claimed responsibility for Manickathasan's assassination, declaring that he was killed after being found ``guilty'' of four charges, a Colombo-based newspaper said on Saturday. The newspaper quoted the clandestine rebel radio Voice of Tigers as saying that Manickathasan was slain for committing rape, collecting ransom, torturing young men and women and providing information to the military.

Manickathasan's group has been cooperating with the security forces to fight the rebels in the north and in the process was known to haveillegally arrested and detained young men and women suspected of having ties to the LTTE. The rebel radio said the allegations against Manickathasan were taken up by a ``LTTE court'' that found him guilty and decided to ``execute'' him, the Sinhala-language Divina newspaper said.

PLOTE legislator Dharmalingam Sidhathan had on Friday admitted their organisation may have been infiltrated by the separatist Liberation Tigers of Tamil Eelam (LTTE) which is opposed to Tamils co-operating with security forces. Sidhathan also said his party believed that Manickathasan's killing was the work of the LTTE and the PLOTE was holding its own inquiry on the basis of this theory.

``The attack becomes even more serious because it shows that that there is very heavy infiltration of the PLOTE,'' a military officer said here on Friday. The PLOTE co-operates with government forces in battling the LTTE.