Gun battles left at least two people dead in Gaza City after about 20 armed militants posing as Palestinian policemen ambushed and killed a senior security official.

The killing of riot police chief Rajah Abu Lehiya took place on Monday morning as the Gaza Strip was in uproar following a major Israeli incursion into the Palestinian-controlled town of Khan Younis in southern Gaza.

[Abu Lehiya's killers wanted' to spread tension and conspiracies among our people at a time when the Israeli occupation continues its crimes against our people

Palestinian police statement

Colonel Abu Lehiya's life was known to have been under threat since his forces broke up a pro-Osama bin Laden rally in Gaza a year ago, killing at least two supporters of the Palestinian militant group Hamas.

The group has distanced itself from Monday's killing, which was claimed by a relative of one of the Hamas members killed at the rally.

Police said Abu Lehiya's car was stopped by 20 armed men dressed in the uniform of the intelligence forces as he drove through central Gaza on Monday morning.

When the car stopped, a large group of the uniformed men surrounded the car, kidnapped Abu Lehiya and drove him off to a Hamas-controlled neighbourhood.

Fourteen people were killed in the Khan Younis raid

The police said he was then shot at least six times and his body dumped on the streets, before the killers drove to Nusseirat refugee camp where they abandoned the car.

Police said Imad Akel, a brother of one of those who died at the 8 October 2001 rally, appeared before a crowd of residents in Nusseirat and declared he had taken revenge for his brother's death.

Hamas official Abdel Aziz Rantisi distanced the group from the killing, saying it was a question of "family revenge" involving the Akel clan.

Further clashes

In the hours after the killing, clashes erupted in central Gaza City between the police, Hamas gunmen and other Palestinians who began throwing stones at the police when they tried to arrest suspects.

Two men were shot dead in the confrontation and 15 people were injured. The dead were named as Mahmoud al-Borno, 27, and Mohammed Hejazi, 30.

A BBC correspondent in central Gaza says gunfire continued intermittently following the incident although it was not clear who was shooting at whom.

The killing of Palestinian officers by militants is rare, but correspondents say there is a now a real possibility of confrontation between Hamas and the Palestinian Authority.

A police statement said the aim of Abu Lehiya's killers was to "spread tension and conspiracies" in the midst of the ongoing Israeli occupation.

Hamas has been behind the most deadly suicide bombings against Israel during the two-year-old Palestinian uprising against Israeli occupation in defiance of the PA's declared policy not to attack civilians.

Last year's demonstration took place outside Gaza City's Islamic University on the day after the United States began bombing Afghanistan. It degenerated into armed clashes, with each side blaming the other for the deaths.