British Prime Minister Tony Blair's government on Monday backed US claims that Iran's leadership has provided weapons to insurgents fighting coalition forces in Iraq. Blair first expressed concern in October 2005 about technology for roadside bombs and other weapons entering Iraq from Iran, the prime minister's official spokesman said. "The prime minister has been at the cutting edge of identifying this problem," the spokesman said on condition of anonymity, in keeping with government policy. "We continue to say what actually is the case, which is that we keep finding this weaponry which we do not believe can be sourced from anywhere else." On Sunday, US military officials in Baghdad accused Iran's leadership of arming Shiite militants in Iraq with sophisticated armor-piercing roadside bombs that have killed more than 170 troops from the US-led coalition. Military officials allege the weapons have been supplied to "rogue elements" of the Mahdi Army militia of anti-American Shiite cleric Muqtada al-Sadr. Many key Iraqi government figures and members of Iraq's Shiite political establishment have deep ties to Iran, having spent decades there in exile during Saddam Hussein's rule.