Britain and the US urged President Mugabe to respect the will of the Zimbabwean people but stopped short of voicing open support for Morgan Tsvangirai.
In the Commons, the Foreign Secretary, David Miliband, praised Mr Tsvangirai for being "statesmanlike", saying the delay in announcing the official results from Saturday's election was a "deliberate and calculated tactic". He added: "It gives substance to the suspicion that the authorities are reluctant to accept the will of the people. They have a responsibility to do so."
The White House said America expected "the will of the people of Zimbabwe to be respected".