Al Jazeera's Minelle Fernandez in Colombo said that LTTE casualties could not be independently confirmed.
"This latest attack is what we heard as far as the military has been claiming…but of course these claims are not verifiable on the ground, but in terms of what we've been hearing, the government has been notching up significant gains," she said.
"We also heard that the air force jets had pounded a key LTTE base which the government says was a gathering place for some of the senior LTTE leaders."
Sri Lanka blocks journalists from traveling to the frontlines, making it impossible to verify casualty claims.
"There are some 200,000 civilians caught between the fighting and we've heard conflicting reports that the LTTE is preventing civilians from moving out of the battlefield and into the safer areas," Fernandez said.
"We also heard that aid agencies were given until Tuesday to move out of the battle zones, but due to the situation becoming dangerous, the government cannot guarantee safety for aid workers."
The northern Kilinochchi district, where much of the fighting took place, is a LTTE stronghold.
Mahinda Rajapakse, the Sri Lankan president, said this week that his forces hope to capture the region by December.
The army ejected the rebels from the east of the island last year.
The miltary says the LTTE has lost 6,662 fighters since January and put its own loss at 646 soldiers killed.