Ken Livingstone is to visit Venezuela next month to offer support to President Hugo Chavez as he seeks re-election in his country.
Mr Livingstone said he was keen to work with Mr Chavez.
Mr Chavez recently visited London to discuss selling oil to fuel buses.
Mr Livingstone announced the planned visit to central America during a conference on Venezuela at City Hall.
He said offering support to Chavez would "get up the nose" of George Bush, but there were many reasons to back the Venezuelan president.
Speaking at the conference Mr Livingstone said: "We're not just supporting the Venezuelan regime because it's nicer to its people than its predecessor or because it gets up the nose of George Bush - though that would be reason enough.
"We work with the government in Caracas as we work with other emerging progressive governments - to create a new world order that can sustain life on this planet."