Peace broker Norway struggled to clinch a deal over new dates for two more rounds of face-to-face negotiations in December and January, but the parties were bogged down over details, diplomats close to the talks said.
Tamil Tiger rebels said the outcome of the first day with government representatives was "zero", with no agreement on their key demand and they accused government forces of preparing for a fresh offensive.
"I would say there was no progress after day one," their chief negotiator, S. P. Thamilselvan said. "We did not hear of any steps that would indicate progress. The progress was zero."
He said the "core issue" for his Liberation Tigers of Tamil Eelam (LTTE) was to address the humanitarian needs of Tamils affected by the recent fighting and the re-opening of the single highway into the northern Jaffna peninsula.
A Sri Lankan government delegate, who declined to be named, said that no progress had been made Saturday and noted that there was little scope for compromise as they met for the first time in eight months.
The negotiator said: "The government delegation is not in a position to agree to the LTTE demands because of the military implications."
The LTTE's military spokesman, Rasiah Ilanthiriyan, who is also in Geneva for the talks, said government troops were preparing to launch a major offensive against rebel-held territory in Jaffna.
"There is a heavy troop build up along the front lines at Muhamalai, Nagarkovil and Kilali," Ilanthiriyan told AFP. "This could have serious consequences for the entire peace process."
He said both sides were exchanging artillery and mortar fire, but he did not have details of casualties.
The Sri Lankan military has also accused the Tigers of launching long-range attacks against security forces in a bid to draw fire from them.
The resurgence in violence since the last talks in Switzerland eight months ago has claimed about 3,000 lives and forced more than 200,000 to flee their homes, according to relief agencies.
At least five people were killed in clashes overnight, Sri Lankan police and defence officials said Sunday.
Hopes of a breakthrough in the peace talks were raised Saturday when the Sri Lankan government climbed down from its rigid position and agreed to consider sharing power in a system similar to the current situation in neighbouring India.
The government has opposed a federal system, although a previous administration in December 2002 agreed with the Tigers to work towards granting extensive devolution of power within a federal constitution.
However, the Tigers said there was no firm offer on the table by the government during the discussions at the Geneva International Conference Centre on Saturday.
The LTTE's Thamilselvan said the Tigers were willing to fully cooperate with truce monitors and the Norwegians to implement the February 2002 cease-fire, which now remains only on paper.
He said they were looking for an immediate response from the government to re-open the highway to Jaffna, which has been cut since August. Sunday's talks focused on the highway issue, diplomats said.
Norway's International Development Minister Erik Solheim warned both sides that the international community was running out of patience. The Tigers, who have been fighting for independence for the Tamil minority, run the risk of greater international isolation while the government could lose foreign aid.
Speaking on behalf of Sri Lanka's key international backers -- the European Union, Japan and the United States -- Solheim urged Colombo and the LTTE to resolve Asia's longest and the bloodiest separatist conflict which has claimed over 60,000 lives since 1972.

Copyright AFP (Agence France-Presse), 2006