The New York-based rights watch group has termed "cynical" the call for probe by Vinayagamurthi Muralitharan aka Karuna, currently the deputy minister of resettlement in the UPFA coalition led by President Mahinda Rajapaksa, given the minister's alleged "prominent" role in the war crimes.
"The Sri Lankan government should act on the call by a government deputy minister to investigate war crimes by examining his own role in serious abuses", a statement said.
In June 1990, 400 to 600 police officers who had surrendered to LTTE forces, many of whom may have been under Karuna's control, were bound, gagged and beaten. The LTTE then executed the Sinhalese and Muslim police officers among them, the HRW said.
The group says Karuna has admitted in an interview with the BBC that the LTTE committed these killings, but claimed he was not at the scene.
Also Read
The global watchdog also charges that Karuna's forces played a prominent role, routinely visiting Tamil homes to tell parents to provide a child for "the movement".
The LTTE harassed and threatened families that resisted, and boys and girls were abducted from their homes at night or while walking to school, it says.
"Karuna has enjoyed immunity for some of the worst atrocities committed during Sri Lanka's long conflict," Adams said.
"His threat to initiate investigations against a political party is a cynical gesture aimed at silencing the opposition while denying his own responsibility for war crimes," he said.
Karuna was effectively the second-in-command of the LTTE and the head of its Eastern Province forces until he broke away from the group's leader, Vellupillai Prabhakaran, in March 2004.