Colombo, Sri Lanka ? An armed group attacked a Tamil Tiger rebel checkpoint Saturday in eastern Sri Lanka, killing two guerrillas in what the rebels called a “serious” violation of the country’s cease-fire.

The rebels said the attackers retreated toward a government base and accused the army of harboring them.

Military spokesman Brig. Sudhir Samarasinghe called the claim “rubbish” and rejected any suggestion that the military was involved.

A senior Tiger rebel leader known as Karuna left the group in 2004 with about 6,000 fighters.

Saturday’s fatalities were the first since peace talks last month in Geneva, where the Sri Lankan government and the Tigers agreed to abide by a 2002 cease-fire.