Pressure is growing for the Home Office to rethink its policy of deporting failed Zimbabwean asylum seekers back to their home country.
The Zimbabwe government is destroying 'illegal' housing
Shadow foreign secretary Dr Liam Fox said deportations should be stopped if proof showed deportees were mistreated by President Robert Mugabe's regime.
Labour and Lib Dem MPs have also called for a review, as a hunger strike among Zimbabwean detainees spreads.
The government insists it is safe to return failed applicants to Zimbabwe.
Dr Fox said the government should ban deportations to Zimbabwe "if reliable evidence comes to light that any of those deported so far have been victims of the Mugabe regime".
He added that it was "very odd" the foreign secretary was denouncing a campaign of housing demolition and clearance by Robert Mugabe, while at the same time the home secretary was saying it was safe to send people back to Zimbabwe.
"I think the government needs to be urgently reviewing their policy to try and get it consistent," he told BBC News 24.
Forty-one Zimbabweans in Britain are starving themselves in protest at the lifting of a ban on deportations in November.
In the first three months of 2005, 95 Zimbabweans were forcibly removed from the UK and 116 are scheduled to be returned to the country.
The criticism of the government came as Zimbabwean opposition leader Crispen Kulinji, who was due to be deported on Saturday, secured a last-minute reprieve, with the help of Labour MP Kate Hoey.
Senior Labour MEP Richard Howitt demanded "urgent action" from the government, which he accused of turning a "blind eye" to the evidence.
The MEP - who speaks on foreign affairs and human rights for Labour MEPs and is vice-chairman of the human rights sub-committee of the European parliament - also called for a sport and cultural boycott of the southern African state.
18 May: Zimbabwean police begin crackdown on illegal traders
26 May: Demolition of homes begin in the capital, Harare. Tens of thousands are detained; hundreds of thousands are homeless
10 June: Two-day strike in protest against demolitions ends. It is poorly publicised and widely seen as a failure
22 June: Zimbabweans in UK detention centres begin hunger strikes over Home Office policy of returning failed asylum seekers to Zimbabwe. Forty-one people have joined the protest
23 June: At a G8 foreign ministers' meeting in London, Jack Straw expresses 'profound concern' about the demolitions
24 June: Zimbabwe's President Robert Mugabe dismisses the G8 criticism. The African Union rejects calls to intervene
Mr Kulinji, 32, from Harare, an organising secretary and election co-ordinator for the Movement for Democratic Change opposition movement, is recovering from injuries he claims he sustained in jail in Zimbabwe.
He said he had been on hunger strike since Wednesday, adding: "We would rather live, but it is better to have a dignified death here than go back to face Mugabe."
Mr Howitt said reports by the International Crisis Group and Amnesty International of torture, political killings and assaults against opposition groups within Zimbabwe challenged the government's position.
"What the government has said is that there are no specific reports of abuse against people who have been returned since the ban was lifted in November," he said.
"I don't think we can have any real confidence that those returned will be safe."
'Not economic refugees'
Liberal Democrat home affairs spokesman Mark Oaten joined in the criticism.
"As the situation in Zimbabwe becomes more and more unsettled the Home Office should be cautious about sending people back to an repressive regime," he said in a statement.
"It is no longer safe to assume that Zimbabwe can provide standards acceptable to the international community."
Zimbabwe opposition leader Morgan Tsvangirai said those being held in the UK were "not just economic refugees".
"They are real political refugees because of the conditions back home," he said.
The Home Office said none of those who had been scheduled for removal were assessed to be in danger if sent back to Zimbabwe and they had no legal right to remain in the UK.
"Since returns were resumed to Zimbabwe last November, we have received no substantiated reports of abuse of any person returned to the country," said immigration minister Tony McNulty.
At a meeting of G8 ministers on Thursday, Foreign Secretary Jack Straw expressed "profound concern" about Zimbabwe and urged African leaders not to turn a blind eye to the actions of president Robert Mugabe.
Mr Mugabe recently began demolishing illegal houses as part of a campaign to "restore sanity" in urban areas he says are overrun with criminals.
The Home Office said staff were monitoring the welfare of the hunger-strikers to ensure they received appropriate medical supervision.
A spokesman said strikes were taking place at the Harmondsworth detention centre at Heathrow; Yarlswood, in Bedfordshire; and Dover.