The prime minister has received backing for his decision to boycott the EU/Africa summit because of the presence of Zimbabwe's President Robert Mugabe.

Gordon Brown was earlier criticised by European Commission president Jose Manuel Barroso.

The British leader refused to attend the Lisbon gathering because Zimbabwe's leader is attending despite being banned from travelling to Europe.

Instead, the UK is represented at the summit by former international development secretary Baroness Amos, who is not a minister.

Brown has said that he is not prepared to sit down at the same table as Mugabe because of his record of human rights abuses and his "unacceptable behaviour" as president.

But Barroso said that world leaders had to be prepared, on occasion, to meet people they did not approve of.

"If you are an international leader then you are going to have to be prepared to meet some people your mother would not like you to meet. That is what we have to do from time to time," he said.

Foreign secretary David Miliband said it would have been "absurd for the prime minister or myself to sit next to Robert Mugabe through a discussion of good governance and human rights and pretend that there wasn't absolute meltdown going on in Zimbabwe".

"The use that would have been put by our presence by Robert Mugabe would have been quite counterproductive," he said.

And responding to comments from former international development secretary Clare Short that Baroness Amos was being sent "because she's black", the foreign secretary said: "I think that is a bit insulting to Baroness Amos."

"She is a former secretary of state for international development, she is a former leader of the House of Lords, she has got a lot of knowledge about Africa as a whole, not just Zimbabwe," he told BBC Radio 4's World at One.

"I think she will be a very good advocate for the UK and also for the sort of relationship between the EU and Africa that we very much want to see."

Amos also said Brown had taken the right course of action.

Speaking on BBC Radio 4's Today programme she said: "A leader makes his or her own decision about who they will meet and under what circumstances.

"There is no doubt that this summit would become a media circus if Gordon Brown were there in the presence of Robert Mugabe."

Baroness Amos renewed the UK's criticism of the Mugabe regime, under which there are millions of people in need of food aid or fleeing the country altogether.

"The situation in Zimbabwe is appalling," she said.