The United States and its chief ally Britain have warned Iran over its possible involvement in insurgent bomb attacks in Iraq, top officials said on Sunday.
Iran denies meddling in Iraq and says the accusations against it are psychological warfare tied to efforts by Washington and London to report Tehran to the UN Security Council for possible sanctions over its nuclear programme.
British Prime Minister Tony Blair said this month there was evidence that Iran or its Lebanese Hizbollah allies were the source of sophisticated technology used in roadside bombs, known as improvised explosive devices (IEDs), that have targeted British soldiers in southern Iraq.
US Secretary of State Condoleezza Rice said on Sunday that Washington had warned Tehran over the issue.
"We have tried to deliver a message ... about this issue of IEDs in southern Iraq," Rice told reporters while in London for talks with Blair. "We have channels with which to do it. But we use them sternly and pretty specifically to deliver messages."
Washington has no formal diplomatic ties with Iran but occasionally talks to the government through Swiss diplomats in Tehran or Iran's ambassador to the United Nations in New York.
The Iranian ambassador in London, Seyed Mohammed Hossein Adeli, told BBC's Radio 4 his country did not support the use of violence against British troops in Iraq and added that stability in Iraq was in Iran's best interest.
Adeli denied any suggestion Iran had supplied explosive devices to Iraqi insurgents attacking British forces. "We have already rejected categorically any link between Iran and the incidents that have taken place with British troops,~ he said.
He said it was not surprising some explosive devices found in Iraq were similar to Iranian devices because weapons from the two countries' eight-year war still litter the region.
British Foreign Secretary Jack Straw, speaking separately to BBC radio, insisted Britain had evidence linking Iran or Hizbollah to insurgent activity in Iraq.