The war against terrorism may soon spread to countries other than Afghanistan where al Qaeda is operating, Geoff Hoon indicated last night.

The defence secretary argued that "an invasive response" might be necessary where the state was too weak to take action against terrorists.

President Bush has said America will "fight terror wherever it exists". During prime minister's questions yesterday Tony Blair stated his support for Bush's stance.

However, British sources told today's Telegraph that the US administration is split on the issue, with secretary of state Colin Powell currently fighting Pentagon officials who want to target other countries such as Iraq.

The source said: "We take every chance to support Powell and ensure that cool heads prevail."