"The Tigers are holding two police constables we are hoping will be released before talks begin," Trade Minister and peace envoy Jeyaraj Fernandopulle said in an interview in the midst of preparations for the talks in Switzerland.

"The Tigers have requested some people be released ... a reciprocal prisoner exchange."

The talks due to be held in or near Geneva on Feb. 22-23 are seen as a last ditch bid to halt attacks that have killed around 200 soldiers, civilians and rebels in two months and threatened to upend a 2002 truce and rekindle a two-decade civil war.

Beaten up by the Tamil Tigers a year ago during a post-tsunami visit to the island's north, Fernandopulle knows only too well the gulf that divides the rebels and the majority-Sinhalese south.

"Without building trust, there's no point in talking," the envoy, himself descended from Indian Tamils who moved to Sri Lanka 300 years ago, said.

The talks could be the first step in what envoys say will be a long haul towards a final settlement to an armed struggle the Liberation Tigers of Tamil Eelam (LTTE) began in earnest in 1983 to fight what many Tamils see as discrimination by successive Sinhalese governments.

"These are not peace talks. We are going to try and have a working arrangement with the LTTE and then later we can have peace talks," Fernandopulle said. "Trust must come first."

"If both sides are genuine, if the LTTE is genuine, then these talks can be successful, he added. "Despite all the attacks, all the killings, I think the Tigers are genuine."

The Tigers insist the talks must focus on implementation to the letter of the existing ceasefire -- in particular a clause that stipulates the state must disarm paramilitaries the rebels say are attacking them.

They want the government to disarm a renegade rebel faction led by a breakaway commander called Karuna, suspected to be behind a series of attacks in parts of the north and east.