Alistair Darling has hinted at government support for congestion charging by calling for a "national debate" on the subject.

The transport secretary had been careful not to associate himself with London's controversial scheme, the biggest of its kind in the world, before assessing its impact.

But last night he said "we need to seize this opportunity to learn from experience" and admitted mayor Ken Livingstone's plans had worked "far better than some predicted".

The FT describe Darling's comments as "the clearest sign yet that the government is considering road pricing nationally".