Robert Mugabe has been unable to win back control of Zimbabwe's parliament after a partial recount of the 29 March election results failed to overturn any of the original results that gave the opposition the majority of seats.

It means the first defeat in 28 years for Mugabe's ruling Zanu-PF party after Zimbabwe's electoral commission (ZEC) yesterday released seven more results from the recount, changing none. It brings to 13 the number of seats recounted, with 10 remaining to be declared - all in strong opposition-held areas. Zanu-PF would need to win nine to regain control.

Results have still not been released from the parallel presidential poll which the opposition Movement for Democratic Change (MDC) says its leader Morgan Tsvangirai won, beating Mugabe outright. Independent monitors estimate that Tsvangirai won, but fell just short of the 50 per cent threshold to avoid a run-off. The MDC accuses Mugabe of delaying results to rig his victory and has rejected any run-off.

The failure to announce the results, four weeks on from the vote, is causing mounting concern internationally. But late yesterday afternoon the electoral commission said it would invite presidential candidates to verify the results from Monday, before they are released. 'We trust that by Monday this process will have been concluded,' said ZEC chairman George Chiweshe. 'I can't say exactly when the results will come.'

Reporters in Zimbabwe say the electoral commission is making the process extremely difficult to follow, and results are being issued in a haphazard manner. The announcements came after a week of escalating attacks on opposition supporters - Tsvangirai is staying out of the country at the moment because of fears about his safety.

On Friday, armed riot police raided the MDC headquarters and detained scores of people in the toughest measures against the opposition since the elections. Computers and documents were seized in the raid.

The MDC says its activists have been attacked around the country - with at least 10 killed. The police claim that no one has died.

Gordon Brown yesterday called for a United Nations mission to inspect human rights abuses. Brown, who is seeking an arms embargo on Mugabe's Zanu-PF party, said Britain would step up diplomatic efforts ahead of this week's Security Council meeting on the former British colony.

'The coming days will be critical. We will intensify international action around a Security Council discussion on Tuesday. We will press for a UN mission to investigate the violence and human rights abuses,' he said in a statement. 'The whole international community must speak up against the climate of fear in Zimbabwe.'

Zimbabweans are enduring severe shortages of basic goods and an inflation rate of 165,000 per cent - the world's highest. The state-run Herald newspaper called African leaders 'myopic stooges' for joining western criticism of Zimbabwe's handling of the election.

Mugabe is beginning to lose regional diplomatic support over the delay in announcing the results and his attempts to retain power through force. His former allies in the Southern African Development Community last week united in condemning him and barred an arms shipment from being unloaded, causing the ship to be recalled to China. Defiant Zanu-PF officials claimed there was no shortage of arms already in or reaching the country.

'I think for the first time, at a very crucial moment, Mugabe is losing diplomatic support in the region and without that support his ability to survive politically is diminished,' said Eldred Masunungure, a professor of political science at the University of Zimbabwe.

Results so far

MDC and allies: 110 seats before recount

Zanu-PF: 97 seats before recount

23 seats subject to recount

13 of these unchanged

10 seats still being recounted

Zanu-PF would need to gain nine of these 10 to be sure of a majority.