Tony Blair has given "broad" support to controversial US "son of star wars" plans in a move which could spark anger within Labour ranks.

Responding to Commons questions from William Hague, Blair said that the government would "wait for a firm proposal before giving a firm decision" on America's planned missile defence system.

The prime minister's official spokesman, Alastair Campbell, later gave a more definite answer when questioned on whether the system was a good idea, apparently ending months of the government sitting on the fence over the issue.

When asked is the government believed the proposed system was a good idea, he said: "Broadly yes, in that the Americans are the last remaining superpower. They are the only ones who can develop this new technology and they are going ahead with it. Within that we have to work out the specific policy questions that relate to the UK and also what other role we can play within this discussion and dialogue as this is going along."