There has been a surge of violence in the past month with scores of people being killed in rebel attacks.
Both sides meet in Geneva on Oct. 28-29 to try to end the fighting that has killed around 1,000 people since July and made a 2002 cease-fire almost redundant.
"They seem to be following a strategy designed to intimidate the government," Palitha Kohona, secretary general of the state's peace secretariat, which co-ordinates and handles peace dialogue for Colombo, told Reuters in an interview.
"My own view is that they are not going to get any leverage as the result of the violence and terrorism.
Rebel leaders were not immediately available for comment but residents in the northern Tamil-dominated Jaffna region said on Sunday that the LTTE was warning Colombo of a wider conflict.
"Now prevails a war environment ... it is inevitable that the consequences of the aggressive war moves launched by the government would spread throughout Sri Lanka," one Jaffna resident quoted LTTE political wing leader S.P. Thamilselvan as saying on a rebel local TV station.
Kohona said the ongoing violence must not derail the talks.
"I think we must separate the talks from the violence. The talks are designed to create an environment to achieve a sustainable, lasting peace," he said late on Saturday.
Sporadic violence, including mortar and grenade attacks, continued over the weekend in the troubled north and east in the run-up to the first face-to-face talks since February between the government and the Liberation Tigers of Tamil Eelam (LTTE), who are fighting for an independent homeland for the Tamil minority.
On Wednesday, the rebels launched a sea-borne suicide raid on a naval base in the southern city of Galle, losing 15 of their cadres while killing one government sailor.
The attack was the first such strike by the LTTE so far down in the Sinhalese-dominated south, underlying its threat of bringing the war into new areas.
Two days earlier, the rebels rammed an explosives-laden truck into a convoy carrying naval personnel in north-central Sri Lanka, killing about 100 people, mostly sailors.
APPROACHING TALKS THROUGH VIOLENCE?
"To approach negotiations through piles of dead bodies and broken limbs appears to me a contradiction in terms," said the soft-spoken Kohona, sitting in his office on the 10th floor of a heavily guarded building in the heart of Colombo.
But the LTTE's official Web site said Sri Lankan artillery and air strikes were hitting civilians, citing a strike by air force jets last week which it said had killed three children in the north. The military could not confirm the incident.
More than 65,000 people have been killed in the two-decade conflict fuelled by complaints from Tamils about discrimination by the government and sections of the Sinhalese majority.
The government plans to focus in the talks on elections in the restive north and east, the question of child soldiers, and the need for peace to bring development to the region.
Kohona said a pact planned this week between the ruling Sri Lanka Freedom Party (SLFP) and the opposition United National Party (UNP) on several issues including a joint approach on finding a political settlement to the conflict would give more flexibility to government negotiators ahead of the Geneva talks.
The SLFP and UNP are the major parties in the south of the island nation, the Sinhalese heartland.
"Now, for the first time, the south is united," said Kohona, an adviser to President Mahinda Rajapakse on the peace talks.
"This certainly does counter an argument that the Tigers had always used for not seriously engaging in discussions which was that the south was incapable of delivering due to the fractured nature of its politics."

Copyright Reuters, 2006