By Yusri Mohamed

AL-AWJAH, Egypt, April 27 (Reuters) - An Egyptian police officer was wounded in an exchange of gunfire after hundreds of Sinai Bedouin tribesmen attempted to storm a border crossing into Israel, security sources said on Friday.

The security sources said the tribesmen drove up to the crossing in dozens of pickup trucks, all without licence plates, but were forced back when Egyptian border guards opened fire.

Tribal sources say the Bedouin wanted to escape a feared police crackdown over protests after two Bedouin died on Wednesday in a police chase.

Security sources said the attempt to cross to Israel was a bid to embarrass the Egyptian government just after a public holiday marking the return of Sinai after Israeli occupation.

The Bedouin say they suffer economic marginalisation and police harassment.

Hundreds of Bedouin from several tribes have been massed 40 km (25 miles) to the north at another border crossing into Israel since Thursday.

After the death of the two Bedouin the previous day, fellow tribesmen held protests and set fire to dozens of tyres on the main road.

Authorities say the two men had exchanged fire with police after driving through a checkpoint in a pick-up truck with no licence plates, and that one was wanted for killing a policeman.

The deaths seem to have acted as a catalyst for long-simmering Bedouin resentment towards Egyptian authorities. The tribesmen had taken control of the road leading to the border crossing, setting up impromptu checkpoints.

They said they would remain at the border until Egyptian authorities addressed their grievances, and threatened to seek political asylum in Israel if their demands were not met.

Bedouin in 1999 managed to illegally cross the border into Israel after disagreements with other tribes and requested political asylum there, but were returned to Egypt.

Tribal sources at the border crossing on Friday listed among their demands the release of fellow tribesman held without charge by police, better job opportunities and living conditions, and an end to police harassment and "persecution".

An interior ministry spokesman denied any harassment of Bedouin tribesmen.

Egypt blamed a series of bombings in Sinai, the last of which took place in April 2006, on a local Islamist group called al-Tawhid wal Jihad (One God and Jihad), and says the group is made up of Sinai Bedouin with militant views.

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