Sri Lankan air force jets bombed a Tamil Tiger suicide fighter camp near the rebels' northern stronghold on Saturday, the military said, adding it believed it had inflicted heavy losses.
The Liberation Tigers of Tamil Eelam (LTTE) said the air force had dropped bombs a few kilometres away from their nerve-centre of Kilinochchi, but had no details of any damage or casualties.
"The air force has hit a Black Tiger (suicide fighter) base," a military spokesman said.
He said jets had dropped bombs over the village of Iranamadu, around 6 km south of Kilinochchi. "It is reported there were heavy losses inflicted."
The bombing comes after days of air force raids on rebel positions, and is the latest in a string of military clashes and battles that have killed more than 3,000 civilians, troops and Tigers so far this year alone.
In a separate incident earlier on Saturday elite police commandos said they killed four rebels in a gunfight in the eastern district of Ampara, while police arrested a man with seven Claymore fragmentation mines and ten kg of high explosives in the capital overnight.
Claymore mines have been used in a string of deadly ambushes in the north and east and in Colombo in recent months.
Many analysts and ordinary Sri Lankans fear a conflict that has killed more than 67,000 people since 1983 could escalate and spread across the island.
President Mahinda Rajapaksa has flatly rejected rebel demands for a separate homeland for minority Tamils in the north and east, and many fear the conflict could rumble on for years.