By Thomas Harding in Baghdad and Francis Harris
The move came after British and American intelligence officials said they uncovered evidence that Iran’s Revolutionary Guard was providing deadly “shaped” charges to Iraq’s insurgents.
They are also thought to be providing training and other weapons.
A statement by the Foreign Office said: “Any Iranian link to armed groups in Iraq outside the political process, either through supply of weapons, training or funding are unacceptable and undermine Iran’s long-term interest to secure a stable and democratic Iraq.”
Iran had given “many public undertakings” to improve border security, fight terrorism and “not to interfere in Iraq’s internal affairs”.
Britain’s statement came hours after Donald Rumsfeld, the US defence secretary, also accused Iran of smuggling weaponry. He said: “It’s notably unhelpful for the Iranians to be allowing weapons of those types to be crossing the border.”
This created problems for the Iraqi government, coalition forces and the international community. “And ultimately, it’s a problem for Iran,” he said.
Asked if that amounted to an implied threat, Mr Rumsfeld said: “I don’t imply threats. You know that.”
The Anglo-American decision to go public on the issue indicates that London and Washington are extremely alarmed by the development. If Iran’s Shia leadership has thrown in its lot with Iraq’s Sunni-dominated insurgency, coalition forces will face a nightmarish task in restoring a semblance of peace to the country.
The development also raises the possibility that Iran’s newly-installed hardline president, Mahmoud Ahmadinejad, has decided to provoke the coalition in response to the huge international pressure he is facing to end Iran’s nuclear programme.
Coalition casualties have been rising in recent weeks, in part it is believed because of new and more sophisticated explosives. In one incident last month, three British troops died in a roadside bomb attack in Amarah, north of Basra. In another last week, 14 US marines were killed by one of the new devices near Haditha.
A British intelligence source said there were indications that the devices are “increasingly being designed and built in neighbouring Iran and then transported to Iraq”.
American and British officers say the new bombs are similar to those used by Hizbollah fighters against the Israelis in southern Lebanon.
“These are among the most sophisticated and most lethal devices we’ve seen,” an American offiicer told The New York Times. “It’s very serious.”
A well-placed shaped charge, which is designed to concentrate the effect of the explosive’s power in a small area, can penetrate up to several inches of armour.
A British intelligence source said: “Given that just 1lb of C-4 explosive in a crudely-packed shaped charge could pierce seven inches of steel, the larger quantities of explosive that have been uncovered recently have the potential to cause significant damage.”
Iran yesterday denied that it was smuggling arms. “Rumsfeld is trying to cover the US mistakes in Iraq,” said a foreign ministry spokesman.
“The American leaders are under pressure from the international and regional public and the Iraqi Muslim people and to justify their failings they invent a fictitious enemy,” he said.
Five American soldiers were killed in Iraq yesterday, including four by a roadside bomb in the northern town of Baijifour. Iraqi police suggested that their vehicle was struck by one of the new type of explosive.
