Harare - Riot police broke up a student demonstration in Harare, injuring at least four people and arresting three Tuesday, in the first such incident of police violence since the signing of a power-sharing agreement by Zimbabwe's political protagonists a month ago.

The attack on the peaceful demonstration took place just as former South African president Thabo Mbeki began mediating to try and rescue the agreement from collapse after President Robert Mugabe at the

weekend unilaterally allocated to his ZANU(PF) party the most important posts in the proposed power-sharing government.

Privilege Mutanga, a member of the national executive of the Zimbabwe National Students Union, said about 200 students had marched to Zimbabwe's parliament to present a petition protesting over the failure since August of nearly all the country's universities to open for the new academic year.

About 30 riot police, with batons, dogs and firearms, stopped them and told them to send two representatives with the petition to the parliament doors.

"As soon as we did, they arrested them," she said. "Then they charged us, and we scattered. I tried to hide inside a shop doorway, but they saw that I was wearing a ZINASU T-shirt, so they pulled me out and beat me with baton sticks and kicked me."

She was treated for bruising and swelling about her body and face. She said another student had suffered a fractured skull. Clever Bere, the president of ZINASU, was in police custody.

Police appeared to have suspended their outright ban on all public demonstrations following the signing of the agreement on September 15, and allowed several peaceful demonstrations to proceed without interruption.

Until then, any demonstrations, except by President Robert Mugabe's ZANU(PF) party, have been met with force, with sometimes hundreds being savagely beaten - including, last year, Morgan Tsvangirai, who is prime minister-designate under the power-sharing deal - and people being detained in filthy police cells for weeks on end.

Observers say the attack on the demonstration is an indication that Mugabe's regime is resuming its hard-line strategy against the octogenarian dictator's regime as hopes for change falter. (dpa)