The army says it has lost 446 of its own soldiers, but continues to advance on LTTE strongholds in the north of the island.
However, the figures are impossible to independently verify as the government refuses journalists and NGOs access to the main areas of fighting in the north.
The figures would mean that 25 LTTE fighters have died every day in 2008.
The LTTE have not released any statistics of their own.
'Not exaggerated'
Talking to Al Jazeera, Brigadier Udaya Nanayakkara, a military spokesman, said that the figures were not exaggerated.
"There is no exaggeration; it is the Tamil Tigers who are exaggerating the figures."
He refuted assertions that the army has claimed to kill more LTTE fighters in the past few years than the actual population of the north of Sri Lanka.
"It is not so. Because even the uncleared area [the north] has over 200,000 people living in that area. So the LTTE can have the support of these people."
Amnesty International, the human rights group, has said that civilians have been caught up in fighting and might have been counted in the LTTE death toll.
Nanayakkara said: "If they are saying that they don't have any evidence to prove that.
"I can assure you that not a single civilian has been killed during these humanitarian operations carried out."
Lieutenant General Sarath Fonseka, an army chief, said on Saturday that government forces had reduced the LTTE's military strength by about two-thirds to 5,000, with about 200,000 civilians forced to provide logistical support.
The government aims to wipe out the separatist group by the end of this year.
The civil war has been going on in Sri Lanka since 1983 when the LTTE began fighting for a separate homeland for minority Tamils.
More than 70,000 people have been killed in the conflict.