As he began his tour of West Africa last night, Tony Blair said the British government wanted to clamp down on companies which fuel wars in Africa through their exploitation of the continent's natural resources.

The government wants stricter enforcement of OECD rules on responsible business.

"Governments should be supporting those guidelines and encouraging companies to work to them," said a senior official.

Arriving in Nigeria, the prime minister will discuss details for an "African recovery plan" being put together by Britain, Canada, France and other western countries.

Alastair Campbell, the government's director of communications, pulled out of the trip at the last minute, citing a need to concentrate on domestic affairs.

The Oppositon questioned why the trip was going ahead when key African leaders were set to meet in Paris on Friday.