At least four people have died in a grenade attack on a Tamil Tiger office in eastern Sri Lanka, the army says.
It was unclear who carried out the attack in a suburb of Trincomalee. Military officials said a breakaway rebel faction might be to blame.
The pro-rebel TamilNet website said at least seven unidentified gunmen were involved, and that two rebel officials and two civilians had died.
Tensions in the east have risen since a split in rebel ranks last year.
The Tamil Tigers say the military supports the breakaway faction - an allegation the authorities deny.
The government in turn accuses the rebels of killing their opponents, in breach of a ceasefire agreed between rebels and government in 2002.
The truce is still in effect, but peace talks have been stalled for more than two years.