The Guardian reports: Britain’s armed forces are stepping up their contingency planning for potential military action against Iran amid mounting concern about Tehran’s nuclear enrichment programme, the Guardian has learned.

The Ministry of Defence believes the US may decide to fast-forward plans for targeted missile strikes at some key Iranian facilities. British officials say that if Washington presses ahead it will seek, and receive, UK military help for any mission, despite some deep reservations within the coalition government.

In anticipation of a potential attack, British military planners are examining where best to deploy Royal Navy ships and submarines equipped with Tomahawk cruise missiles over the coming months as part of what would be an air and sea campaign.

They also believe the US would ask permission to launch attacks from Diego Garcia, the British Indian ocean territory, which the Americans have used previously for conflicts in the Middle East.

The Guardian has spoken to a number of Whitehall and defence officials over recent weeks who said Iran was once again becoming the focus of diplomatic concern after the revolution in Libya.

They made clear that Barack Obama, has no wish to embark on a new and provocative military venture before next November’s presidential election.

But they warned the calculations could change because of mounting anxiety over intelligence gathered by western agencies, and the more belligerent posture that Iran appears to have been taking.