The Palestinian intelligence chief was badly wounded on Saturday when an elevator he was taking at his headquarters in the Gaza Strip exploded in what his ally President Mahmoud Abbas called an assassination bid.

The new Hamas police march during a Hamas rally at the Nussirat camp in Gaza strip May 19, 2006. [Reuters]

One of General Intelligence chief Tareq Abu Rajab's aides was killed in the incident, inflaming tension between gunmen from Abbas's Fatah faction and militants from the rival Hamas movement which heads the government.

A boy was later wounded in the crossfire of a gunfight that erupted between militants close to Rajab and members of an alternative militia Hamas formed last month in parallel to Abbas's security forces, witnesses said.

The new violence broke after Hamas militants tried to clear burning tyres demonstrators had put on the street. Dozens of members of the family of Rajab's aide and Fatah supporters protested against the new force, chanting, "Fatah, Fatah!" Tension has been rising in Gaza after the Hamas-led government, elected in a January parliamentary vote, formed the 3,000-strong Hamas backed force, under the authority of Interior Minister Saeed Seyam, to challenge Abbas.

Rajab was taking an elevator surrounded by a phalanx of bodyguards and aides when it exploded, apparently when a bomb planted in the lift shaft was detonated, security sources said.

Abbas and the interior minister immediately ordered an investigation into the incident, which Abbas called an "assassination attempt".

Rajab, chief of the "mukhabarat" intelligence service, was among 11 people wounded in the blast at his heavily guarded headquarters in north Gaza. One of his aides, a nephew, died.

Rajab, who suffered severe leg wounds, and a bodyguard were taken to an Israeli hospital for treatment following a request for medical aid by Abbas, an Israeli liaison official said.

HAMAS SUSPECTED

Tawfiq Tirawi, a top security official in the West Bank who serves as Rajab's deputy, indicated to reporters at a news conference that Hamas militants from the new security force might be responsible for the explosion.

Tirawi said the Hamas "militias" have recently been buying and collecting weapons and explosives. Several Palestinian officials said Hamas has been purchasing arms in the West Bank and Gaza since it won a parliamentary election in January.

There was no immediate comment from Hamas.

Five people were wounded in gunbattles between Fatah and Hamas supporters in the Gaza Strip on Friday.

The fighting erupted after top Hamas official Sami Abu Zuhri was caught trying to bring 639,000 euros ($804,000) into Gaza. He said on Saturday that the money would soon be transferred to the Finance Ministry.

Hamas also was accused of being behind a 2004 assassination attempt against Rajab in which he was shot by unidentified gunmen and sustained severe wounds. Hamas denied responsibility.

In parallel to the Hamas force, Abbas ordered the deployment of a Fatah-loyal police unit. Fatah supporters said in a statement that thousands of Fatah loyalists would deploy across Gaza if the Hamas force did not disband within three days.

Dozens of Fatah gunmen surrounded the Palestinian parliament in the West Bank city of Ramallah in a show of force after the Rajab attack and issued a leaflet urging Abbas to dissolve the Hamas-led government and call new elections.

The Hamas-led Palestinian government is shunned by Israel, the United States and other world powers and faces international aid cuts unless the militant Islamist movement renounces violence, recognises Israel and embraces existing peace plans.

Hamas leaders have so far refused to moderate the positions of the group, which is sworn to Israel's destruction.

Prime Minister Ismail Haniyeh has vowed not to disband his new Hamas-led security force and said he might increase its numbers in defiance of Abbas and the United States.