Morgan Tsvangirai, the Zimbabwean opposition leader, has agreed to join a unity government with President Robert Mugabe amid intense regional pressure and warnings that the deadliest cholera outbreak in Africa for 15 years threatens to get worse.

Tsvangirai made the announcement after a meeting of the Movement for Democratic Change's national council, which had been divided on whether to accept a settlement proposed this week by the Southern African Development Community (SADC). "We are unequivocal, we will go into this government," Tsvangirai told reporters in Harare. "The SADC has decided and we are bound by that decision."

Tsvangirai is due to be sworn in as prime minister on 11 February, with ministers taking office two days later.

While the mistrust between Tsvangirai and Mugabe remains, and a number of contentious issues have yet to be decided, the political thaw will raise hopes that the country's disastrous economic and health situation can now be eased.

The World Health Organisation said yesterday that 69 Zimbabweans had died of cholera in the previous 24 hours, taking the number of deaths to 3,161 since August. The total number of infections was more than 60,000, surpassing the organisation's "worst-case scenario".

On Thursday it emerged that the United Nations is to halve its food rations to 7 million Zimbabweans, about 70% of the country's remaining population.

The World Food Programme says it cut the ration to meet increased demand and cope with a shortfall in donations. International donors have refused to provide financial aid until a unity government is in place.

The MDC and Mugabe's ruling Zanu-PF party originally agreed to share power on 15 September after controversial elections that saw Tsvangirai win the first round of the presidential poll but abandon the run-off due to state-sponsored violence. The agreement soon fell apart when Mugabe, who has held power since 1980, refused to divide the key ministries fairly. Police then arrested dozens of MDC activists and officials on dubious grounds, and many of them remain in custody.

With the effects of Zimbabwe's meltdown spilling into neighbouring countries, SADC leaders have been desperate to get a coalition government in place.

Analysts say that if Tsvangirai had walked away from the power-sharing option, he could have faced domestic criticism for putting his own interests ahead of the country.