A Chinese ship carrying arms for President Robert Mugabe's government in Zimbabwe was today steaming northwards through the Indian Ocean after dockers and police in the South African port of Durban refused to unload the cargo vessel.

The ship's departure came as Zimbabwe yesterday began a partial recount of votes from the March 29 elections, despite opposition efforts to block the move and widespread fears that political stalemate could erupt into violence.

The recount in 23 of 210 constituencies could overturn the results of the parliamentary election, which have not so far been officially announced. It is generally believed that they show Mugabe's ruling Zanu-PF clearly losing its majority to the opposition Movement for Democratic Change for the first time.

"The vote recounting process has started, and it's going to be a thorough exercise. We expect it to take about three days," said an official from the Zimbabwe Electoral Commission.

The commission says some foreign observers will be allowed to monitor the recount, but concerns continue in the West and among the opposition that Mugabe's government is planning to rig the outcome.

A delegation from the 14-nation Southern African Development Community (SADC) will be present, with South Africa's foreign affairs deputy director-general for Africa, Kingsley Mamabolo, leading the mission. It is unclear, however, when the results of the recount, which includes votes cast in the presidential election, will be announced.

Meanwhile, the humiliating retreat of the Chinese vessel the An Yue Jiang may yet come to be seen as a turning point in the struggle to bring an end to the 29-year Mugabe regime.

The dockers and police defied South African president Thabo Mbeki and his African National Congress (ANC) government, who said the 77 tonnes of weapons for the Mugabe government aboard the An Yue Jiang were legal cargo and would be transported 1000 miles overland northwards to Zimbabwe.

The South African government gave customs clearance for the weapons, which include more than three million rounds of AK-47 rifle ammunition, 1500 rocket-propelled grenades and more than 3000 mortar rounds and launchers.

But Randall Howard, general secretary of the South African Transport and Allied Workers Union (Satawu), to which the Durban dockers belong, warned: "As far as we are concerned, the containers will not be offloaded. The ship must return to China. If they the Mbeki government bring replacement labour to do the work, our members will not stand and look at them and smile."

South Africa's police trade union warned Mbeki, widely seen as sympathetic to Mugabe, against using policemen as "scab" labour.

"The dockers have good reasons for not offloading the ship," said Benzi Soko, spokesman for the Police and Prisons Civil Rights Union (Popcru). "We understand their objection."

South Africa is seen as the one country that could bring the Mugabe government to its knees and force it to hold truly free and fair elections that could see opposition movements take power. They would be faced with reconstructing a country with 1650% inflation, 82% unemployment and the world's lowest life expectancy among women - 34 years, against nearly 60 at independence in 1980.

It was the former white apartheid government in South Africa that forced the white colonial regime led by Ian Smith in Zimbabwe, then called Rhodesia, to negotiate a transfer of power to black nationalists after Pretoria's decision to stop supplying weapons to Smith and cut off other essential supplies.

Analysts argue that South Africa, the continent's economic superpower, could bring the same pressure to bear on Mugabe if Mbeki so chose.

But Mbeki has opted for a policy of "quiet diplomacy" towards Zimbabwe, which is widely seen as a tilt towards Mugabe for reasons that no analyst has yet fully fathomed.

Many South Africans are disillusioned with this approach. They accuse Mbeki of emphasising loyalty to Mugabe, a former black liberation struggle icon, over the rights of ordinary Zimbabweans.

And last weekend, when Mbeki flew north to meet Mugabe prior to a summit of 14 southern African leaders in Zambia, he emerged from their talks holding Mugabe's hand and said that there was "no crisis" in Zimbabwe.

Mbeki's utterance drew strong international condemnation, but it particularly angered South Africans, who daily see the obvious proof of a crisis in the three million Zimbabwean refugees - a quarter of Zimbabwe's population - in their country, begging at almost every crossroads.

Many senior figures in the ANC, from the leadership of which Mbeki was ousted last December over issues that included Zimbabwe, have contradicted his position.

ANC leader Jacob Zuma, who hopes to succeed Mbeki as state president when the latter's term of office expires in a year's time, last week spoke of a "deepening crisis" in Zimbabwe, a blunt rebuttal of Mbeki's "no crisis" declaration.

Zuma recognises the groundswell of public opinion in South Africa for strong action to be taken against Mugabe. Many of the Zimbabwean refugees, whose numbers swell by more than 4000 each day, are blamed by South Africans for increasing crime and draining social services.

Mbeki, chairing a session of the UN General Assembly in New York last week, sat stony-faced when the British prime minister Gordon Brown, just two places away from Mbeki, said it was obvious that Mugabe was trying to overturn an election that had gone against him.

"No-one thinks, having seen the results at polling stations, that President Mugabe has won this election," Brown said. "A stolen election would not be a democratic election at all."

Mbeki subsequently cancelled a scheduled meeting with Brown and, using South Africa's rotating membership of the Security Council, he blocked the council from addressing the Zimbabwe issue.