I wouldn't rule out attack on Iran, says Cameron

The Conservative leader yesterday accused former Foreign Secretary Jack Straw of diplomatic blundering when he ruled out the use of force against Tehran, and called for much tougher diplomacy to halt Iran's nuclear ambitions.

His tough rhetoric came as British Army officers in Afghanistan said they were now fighting an "undeclared war" against Iranian-backed militias, supplied with increasingly deadly weaponry from across the border.

And security analysts said Iranian spies have been carrying out reconnaissance trips at nuclear power stations in Europe - apparently planning revenge terror attacks in case the West tries to disable Iran's own nuclear facilities.

Intelligence sources said security has been stepped up around key British sites in response, including critical oil and gas terminals.

Concerns have grown in recent months over the flow of deadly weaponry being supplied from Iran to insurgents in both Iraq and Afghanistan. Mr Cameron yesterday demanded tougher UN and European-Union sanctions to force Tehran to halt its nuclear weapons programme.

If Iran fails to comply, he said, a Tory government would back Washington in strikes against the rogue state.

He said: "I think [US Secretary of State] Condoleezza Rice is right to say it is not on the agenda, but I think Jack Straw was wrong to rule it completely out of order.

"I don't think it is ever sensible in international affairs to rule things completely out and I wouldn't take that path."

He said it would be a "calamity" if Iran develops a nuclear weapon, adding: "Make no mistake: The threat is growing. The scale and urgency of our response needs to match it." '

Mr Cameron and Shadow Foreign Secretary William Hague said Britain should spearhead a "rapid" shift in policy on Iran by using its influence in the EU, UN and with the U.S. to beef up "weak" sanctions.

Tory MP and former infantry commander Patrick Mercer yesterday revealed a recent email from a friend serving in southern Afghanistan, stating: "We are fighting an undeclared war over here against Iranian-backed militias."

And Army sources claimed members of Iran's fanatical Revolutionary Guard are supplying the Taliban with Soviet-designed SA-7 Strela surface to air missiles, capable of shooting down helicopters on which UK forces in Afghanistan rely heavily.

UK troops are being attacked with more sophisticated RPG-29 anti-tank rockets which carry warheads designed to cut through the best tank armour, as well as increasingly powerful roadside bombs which produce a rod of molten metal capable of slicing through thick steel armour.

Addressing a security briefing at the Commons, Mr Mercer said: "These are not improvised bombs knocked up in a back shed. They are factory-grade weapons being manufactured and used with considerable expertise, to devastating effect."

In an attack in April on UK forces in Iraq's Maysan Province, insurgents staged an elaborate ambush with more than 40 of these bombs, Mr Mercer said, killing two men from the Queen's Royal Lancers.