Gordon Brown has thrown plans for a summit of African and European leaders into turmoil by vowing to pull out if Robert Mugabe of Zimbabwe takes part. The Prime Minister, normally keen to promote Africa, believes that his boycott would be followed by several European allies and is hoping that the threat will stop Mr Mugabe from being invited.

But it has left Portugal, holders of the rotating EU presidency, in a quandary. Some African leaders have said that they will not attend if Mr Mugabe is banned. Formal invitations to the gathering in Lisbon in December will be sent out this month and the Portuguese are struggling to find a solution to save the summit. If the meeting collapses Mr Brown could find himself blamed for setting back Europe’s relations with Africa, while China is stepping up its business dealings with the continent.

A previous attempt to hold an EU/Africa summit failed in 2003 because of a row over Mr Mugabe and there are a host of key isues on the table, from climate change to migration and the humanitarian crisis in Darfur.

The Prime Minister is eager not to find himself in the same position as Jack Straw who, as Foreign Secretary, shook hands with Mr Mugabe at the United Nations in New York in 2004.

Mr Brown’s threat was delivered to EU foreign ministers by David Miliband, the Foreign Secretary. He was “clear that there is serious business to be done at the EU/Africa summit and it would be overshadowed by a Mugabe circus,” a source said.

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