CELIGNY, Switzerland (AFP) -- Embattled Sri Lanka may have borrowed time after talks at this serene Swiss village where the South Asian nation's warring sides agreed to stop the killings till summer.

A top leader of the Tamil Tiger rebels, S. P. Thamilselvan, told AFP here that they gave the Colombo government two months to make good on the promises made during two days of talks or risk a return to hostilities.

Thamilselvan, head of the political wing of the Liberation Tigers of Tamil Eelam (LTTE), one of the world's most ruthlessly efficient guerrilla outfits known for suicide bombings, said he had little confidence that Colombo will deliver.

"The declarations and words should be translated into action," Thamilselvan said at the Chateau de Bossey, an 18th century building surrounded by woods and vineyards, overlooking Lake Geneva.

"Two months is amply sufficient (for the government) to demonstrate its sincerity," he said adding that the hostilities could result unless the government moved to rein in paramilitary groups.

Thamilselvan maintained that the Tigers were not responsible for a spike in violence between December and January when some 153 people, mostly security personnel, were killed in the island's restive northern and eastern regions.

"We did not carry out the attacks, it was the work of civilian groups that were unhappy about the government's support to paramilitary groups," Thamilselvan said.

Thamilselvan added that the Tigers will engage Tamil "civilian groups" to ensure there will be no more attacks against security forces, at least until the next round of three-day talks starting April 19.

The two sides whose mutual confidence had hit rock bottom agreed to hold a new meeting then on strengthening the troubled ceasefire and that decision was hailed by diplomats as a major breakthrough.

However, Thamilselvan was dismissive of the government's promise to implement the truce fully.

He said that declarations in the past had been divine but that the devil was in the implementation. "The ceasefire agreement we entered into four years ago is good, but we don't see the government implementing it fully," he said. "That has been our experience in dealing with Sinhala (majority) governments in the past."

The latest meeting which ended on Thursday here was the first high level encounter between Colombo and the Tigers in three years and there was much debate over a venue until they agreed to meet in neutral Switzerland.

During other European talks, Thamilselvan in December 2002 had thrown snowballs at his military-wing colleague V. Muralitharan, better known as Colonel Karuna, but this week missed out both on Karuna and snow.

He declined even to discuss Karuna, who led an unprecedented split in March 2004 and is now posing a serious challenge to the LTTE's supremacy in the island's north-east. "We don't consider Karuna as a matter that we can even consider," Thamilselvan said. "He is a traitor and is engaging in actions against the Tamil people."

The chilly Alpine climate did not lower the temperature at the two-day negotiations here. "Yes, the climate was cool but the discussion was very heated," he said.

Tiger rebels extracted an agreement from Sri Lanka to uphold their controversial truce after threatening a walk out, the rebel chief negotiator Anton Balasingham told AFP on Friday.

More than 60,000 people have been killed in Sri Lanka's drawn out ethnic conflict in the past three decades and four previous peace attempts have ended in failure.

Both sides have agreed to stop the killings at least till their next round of talks and for the 19.5 million Sri Lankans, the clock is ticking.