The civilian death toll from an overnight artillery barrage in northern Sri Lanka has risen to 378, a health official said Sunday.

V. Shanmugarajah, a physician working in the war zone, reported the number as bodies were brought to the makeshift hospital that he runs. He said 1,122 people have been wounded.

The military denies launching the attack, saying it is using only small arms against Tamil Tiger rebels to remove them from their tiny holdout on the northeast coast.

Two weeks ago, the government vowed to stop using heavy weapons, but reports from inside the battle zone say air and artillery strikes are continuing.

Reports of the fighting are difficult to verify because the government bars journalists and aid workers from the war zone.

The TamilNet website said the artillery attack began late Saturday and lasted throughout the night.

The latest casualties come as the government and aid groups struggle to cope with more than 120,000 civilians who have fled the war zone.

Meanwhile, Sri Lankan police detained three journalists for London-based Channel 4 television news Saturday for alleged false reporting on the civil war.

The three were stopped in the eastern town of Trincomalee. They left their hotel in the capital, Colombo, on Saturday, after being expelled from the country.

A Channel 4 news report that aired last Tuesday chronicled allegations of abuse against Tamils war refugees in the city of Vavuniya, where fighting has raged between the government and rebels.

With files from The Associated Press