Conservative demands that Britain "derecognise" Zimbabwe's government have been rejected by foreign secretary David Miliband.
But prime minister Gordon Brown and Mr Miliband made clear their opposition to Robert Mugabe's regime in a damning indictment of the Zimbabwe president's record.
The comments came one day after opposition leader Morgan Tsvangirai announced he would be withdrawing his challenge in Friday's presidential runoff election because of violence and intimidation.
Mr Brown, speaking first, said the UK government did not recognise incumbent Mr Mugabe's regime as "legitimate".
"Our thoughts are with the people of Zimbabwe who are facing an unprecedented level of violence and intimidation from the regime," the prime minister said, describing Mr Mugabe's government as "a criminal and discredited kabal".
Foreign secretary Mr Miliband's statement followed the prime minister's, citing evidence from non-governmental organisations, media and observers to show the British government's stance is not "propaganda".
"The stage was set for the most rigged election in African history. Robert Mugabe and his thugs made an election possible - certainly the notion of a free and fair election farcical," he said.
"We do not recognise the Mugabe government as the legitimate representative of the Zimbabwean people. We do not believe a government which has clubbed its way to victory and has defied the constitution. can claim to be the representative of the Zimbabwe people."
Mr Miliband insisted it would be wrong to cut off links with the Zimbabwe state, however, and said Britain's historic involvement in the country did not mean it could not be involved in international condemnation of the current situation.
"Robert Mugabe's misrule does not invalidate the struggle for independence. Our colonial history does not mean we cannot denounce that which is wrong," he added.