Western governments and the UN expressed alarm Thursday as top Zimbabwe opposition figure Tendai Biti was detained after a failed attempt to flee to neighbouring Zambia and claim asylum.
Biti, a veteran figure in the opposition Movement for Democratic Change (MDC), made a dash across the border Wednesday, facing allegations of inciting post-election protests at home.
Zambian authorities rejected his asylum claim and handed him back to Zimbabwean police — in defiance of a court ruling, according to Biti's lawyers.
The UN refugee agency said it was "gravely concerned about reports of the forced return" of Biti, an internationally-respected finance minister in Zimbabwe's 2009-2013 power-sharing government.
"Forcibly returning refugees and asylum-seekers to their country of origin is a serious violation of international refugee law," the UNHCR said in a statement.
It urged Zambia to investigate the incident, which comes after accusations that Zimbabwe's authorities are pursuing a heavy crackdown on the opposition over its claims that last week's landmark elections were rigged.
Zambian government spokeswoman Dora Siliya said authorities had only received the ruling blocking his expulsion after it was too late.
"The court order only came after he was handed back to the Zimbabwe authorities," she told AFP.
"His asylum was denied on the basis that in his country there is no breakdown in the rule of law," she said, adding that Biti himself was "running away from the due process of the law" as he was wanted by authorities.
Western nations said they were "deeply disturbed by continuing reports that opposition supporters are being targeted by members of the Zimbabwean security forces".
In a joint statement, the EU, US, Canadian and Australian missions to Zimbabwe urged authorities to "guarantee the physical integrity and safety of Mr Biti, to ensure that his constitutional and human rights are respected, and that he will be treated in full accordance with the rule of law".
Zimbabwe Lawyers for Human Rights, a non-profit organisation, said Biti had been taken to Harare's central police station.
MDC leader Nelson Chamisa said he was "extremely concerned" by Biti's situation.
Chamisa has repeatedly charged that the July 30 presidential election, the first since veteran autocrat Robert Mugabe was ousted by the military in November, was stolen from him.
The MDC will launch its legal challenge against the results later Thursday, Chamisa said.
Mugabe's successor President Emmerson Mnangagwa was last week declared the winner with 50.8 percent of the vote — just enough to avoid a run-off against Chamisa.
According to Zimbabwe's state-run Chronicle newspaper, Biti is among nine suspects sought for inciting protests against alleged rigging which turned deadly on August 1.
The army opened fire on the protests in Harare, killing six people and prompting an international outcry.
Mnangagwa, who is seeking to reverse Zimbabwe's economic isolation and attract desperately needed foreign investment, had vowed the elections would turn a page on Mugabe's repressive 37-year rule.
But the aftermath of the polls has been marred by allegations by rights groups as well as the MDC of a crackdown on opposition members, including beatings and arrests.
Biti's deportation was likely to come up in talks between South African President Cyril Ramaphosa and his Zambian counterpart Edgar Lungu in Lusaka on Thursday.
In a statement, the South African presidency also said Ramaphosa would also fly to Zimbabwe for Mnangagwa's inauguration on Sunday, but this could be delayed by Chamisa's legal challenge.
MDC lawyer Thabani Mpofu said on Wednesday that the election results "grossly mathematically fail to tally".
He said the party would reveal "a secret weapon" in court, but analysts say the challenge is highly unlikely to overturn the declared results.
The Zimbabwe Election Commission — synonymous with fraud under Mugabe — insists the elections were free and fair this time around.
International monitors praised the conduct of the election itself, although EU observers said Mnangagwa benefited from an "un-level playing field" and a degree of voter intimidation.