In an unprecedented move against Zimbabwe's political opposition, police have arrested hundreds of opposition supporters at the headquarters of the Movement for Democratic Change. The police claim they were looking for the party's election data from the March 29 polls. Peta Thornycroft reports from Harare that the police also raided the offices of a non-governmental group that promotes the democratic process, apparently looking for its election data.

For the past two weeks, the reception area and the pavement in front of MDC headquarters in Harare have been full of injured people seeking medical treatment and comfort.

Most struggled in from rural areas where they say they were savagely beaten by people wearing army and police uniforms.

Some people, especially from the northeast, say they were beaten by well- known personalities of the governing ZANU-PF party.

At mid-morning Friday, scores of riot and uniformed members of the Zimababwe Republic Police forced their way into MDC headquarters and climbed the stairs to its administrative section.

According to an MDC security official, who spoke outside the now deserted offices in central Harare, about 300 party officials and supporters were taken away.

He said a large bus and a three-ton truck hauled the detainees away.

The party's computers from its election unit were also taken.

MDC secretary-general Tendai Biti, currently in South Africa, reacted to the raid.

"About 300 included refugees who were already hiding there, fleeing from their burnt and erased homes in the countryside," he said. "Many have got broken limbs, the majority are women and children. So you vandalize people that were already traumatized by the violence that has taken place in the countryside."

He called on the United Nations as well as African institutions such as the African Union to intervene to stop the attacks.

The MDC had an election department which collated results from the March elections which were posted outside polling stations after counting and verification ended.

It presented information after the elections and claimed its presidential candidate Morgan Tsvangirai defeated President Robert Mugabe by about eight percent. The country's Electoral Commission has still not released official results of the presidential election, held at the end of March.

The MDC won a narrow majority in the parliamentary poll which took place on the same day. Some of those results have undergone a recount.

Across town, the police also raided the offices of the Zimbabwe Election Support Network,a coalition of non-governmental groups promoting free elections. The Network's computers and data were taken away.

Noel Kututwa, the chairman, now in hiding, confirmed the raid in a text message to VOA.

The Support Network has presented interim data, claiming MDC victories in all four elections last month -- presidential, parliamentary, senate and local polls. It has still to present its final assessment of the presidential vote, based on data from its own observers and other monitors.

Meanwhile, Nobel Peace laureate Desmond Tutu has called on southern African leaders to urge President Mugabe to step down. Archbishop Tutu spoke on national television in South Africa.

"I am calling on African leaders to persuade Mr. Mugabe to step down and say to him that he does still have the chance of redeeming, of salvaging some of his legacy," he said. "If he continues and remains as obdurate as he appears to be, clearly people are going to be saying no, he must ultimately be arraigned for all of the human rights violations he has perpetrated. But he still has the opportunity, many of us would say, give him the chance of a soft landing."

Questions sent to the police commissioner and security ministers went unanswered on Friday. The MDC's top officials and administrators are mostly in detention, and many of its legislators are in hiding.