Lawyers march through Harare to call for the release of Jestina Mukoko
A High Court judge in Zimbabwe has ordered police to launch a search for a human rights activist abducted from her home last week.
In an unusual move, Judge Anne Gowora said they should hunt for campaigner Jestina Mukoko in all places of detention where they have jurisdiction.
Police deny holding Ms Mukoko, director of the Zimbabwe Peace Project, who disappeared last Wednesday.
The opposition leader said he held President Mugabe responsible for her.
Speaking from neighbouring Botswana, the Movement for Democratic Change's (MDC) Morgan Tsvangirai told the BBC: "These abductions are deliberate attempts to decimate, intimidate and harass the opposition."
He added: "I can only say that Mugabe at this stage is responsible for the lives of those people, and that he should release those people. If they die, they are dying on his hands."
Mr Tsvangirai also said Zimbabwe's cholera outbreak was "catastrophic", as it emerged deaths from the epidemic had climbed towards 800.
A total of 774 people have now died and suspected cases have climbed to 15,219, the UN World Health Organisation said on Wednesday.
South Africa's governing African National Congress party has urged Zimbabwe's government "as a matter of urgency" to find Ms Mukoko and two other missing Zimbabwe Peace Project workers.
The High Court judge ordered national broadcaster the Zimbabwe Broadcasting Corporation to run radio and television appeals for information about Ms Mukoko, who was allegedly abducted from her home outside the capital, Harare, by 15 armed men on 3 December.
There are reports that two days later the brother of a lawyer working on Ms Mukoko's case was taken from his home in southern Zimbabwe, while two of Ms Mukoko's colleagues were abducted on Monday at their workplace.
It has been estimated cholera cases could top 60,000 within weeks
On Wednesday, members of Zimbabwe Lawyers for Human Rights carrying banners protesting against recent abductions marched through the centre of Harare to parliament.
Zimbabwean journalist Brian Hungwe told the BBC emotions were running high but the marchers, who were escorted by police on bicycles, conducted themselves peacefully.
BBC southern Africa correspondent Peter Biles says there is growing concern in Zimbabwe about the number of human rights activists and MDC supporters who have been abducted since October. Some 18 are reportedly missing.
On Monday, an adviser to Mr Tsvangirai was also abducted. Gandhi Mudzwinga was forced into a car by a group of armed men and driven away, said eyewitnesses.
Robert Mugabe's ruling Zanu-PF party and the MDC have been deadlocked in floundering power-sharing negotiations since September over how to divide control of key ministries.
This shows the audacity of a regime that is desperate to stay in power, no matter what the cost
Mr Tsvangirai has not been back in the country since leaving more than a month ago to attend a summit in Johannesburg - where efforts failed again to set up a national unity government in Zimbabwe.
"Zanu-PF expected that after having messed up the country they expect us to clean up the mess without the authority to discharge our responsibilities," the MDC leader told the BBC.
Human rights groups demanded an immediate end on Wednesday to the abduction of activists.
"This shows the audacity of a regime that is desperate to stay in power, no matter what the cost," Irene Khan, secretary general of Amnesty International, said.
Civil rights groups say they are being targeted in Zimbabwe
"The only way out of this problem is through unified pressure from outside, in particular of African leaders."
But so far among African nations, only leaders in Botswana and Kenya have called on Mr Mugabe, who has ruled since Zimbabwe won independence in 1980, to go.
South Africa has rejected calls for the 84-year-old to resign, while the 53-member African Union says power-sharing talks are the way forward.
The Zimbabwe government said on Tuesday the cholera outbreak was under control, a week after declaring it a national emergency.
But up to 60,000 cases of the disease could emerge in the country in the coming weeks, the UN children's agency Unicef has warned.
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