Military intervention in Zimbabwe could be necessary to stop violence sliding into "genocide", Paddy Ashdown has warned.
Lord Ashdown of Norton-sub-Hamdon said the world could not stand by and watch mass slaughter on the scale of Rwanda in the mid-1990s.
The former EU High Representative for Bosnia and Herzegovina said: "The situation in Zimbabwe could deteriorate to a point where genocide could be a possible outcome - something that looks like (another) Rwanda."
In that event an armed response would have to be considered, with Britain playing a "delicate role" due to its colonial history, he added.
Lord Ashdown raised the prospect of military action as international outrage grew over Robert Mugabe's "stolen" presidential election.
Opposition leader Morgan Tsvangirai was forced to seek refuge in the Dutch Embassy in Harare on Monday, after pulling out of the electoral run-off amid vicious attacks on his supporters.
The move sparked a call from Gordon Brown for the international community to refuse to recognise the result, despite Mr Mugabe's Zanu-PF party insisting it would push ahead with the poll on Friday.
In a Commons statement, the Prime Minister said Britain would now be pressing for fresh sanctions against Mr Mugabe's inner circle - including travel bans and the freezing of financial assets held abroad.
The MDC won the parliamentary vote in March, and is widely believed to have won the first round of the presidential contest outright.
However, official results claimed Mr Tsvangirai led but failed to gain enough votes to avoid a run-off.
