Three Lebanese army intelligence officers have been shot dead by unidentified gunmen in the southern port city of Sidon.

They were killed during a raid on the home of a member of an obscure Palestinian militant group which is based in the nearby Ain al-Helweh refugee camp.

Osbat al-Ansar (League of Partisans)

Led by Ahmad Abd al-Karim al-Sadi, aka Abu Mahjan Abu Mahjan sentenced to death in absentia in 1998 for murdering a rival leader Members have been jailed for attacking alcohol vendors in Sidon

The soldiers came under fire about a mile from the camp, which is off-limits to the Lebanese security forces.

Troops sealed off the area as a search for the attackers got under way.

Security sources said the soldiers were seeking to arrest a member of the Osbat al-Ansar group, identified as Badieh Hamadeh.

The group's leader, a Palestinian Islamist, is already on the run from a death sentence issued in Lebanon.

Osbat al-Ansar is suspected by the United States of links to Osama Bin Laden's al-Qaeda network and Washington has ordered its assets to be frozen.

Suspected members of the group were arrested in Lebanon in October 2001 amid reports that they were planning terror attacks on Western interests in the country.

The Ain al-Helweh refugee camp is home to about 75,000 people and is run by Palestinian groups.

Lebanese security forces guard the camp from the outside but do not enter, correspondents report.