Bush 'certain' that Iran supplied weapons to Shia

President Bush has again accused Iran of supplying lethal weaponry to Shia fighters in Iraq but stepped back from claims made by US military officials that the shipments had been approved "at the highest levels" in Tehran.

His remarks came after General Peter Pace, chairman of the joint chiefs and Mr Bush's top uniformed military adviser, appeared to contradict a briefing by senior US officers in Baghdad last weekend, at which they displayed sophisticated explosive devices said to have been manufactured in Iran and responsible for the death of 170 coalition troops. The arms had been sent on the instructions of government leaders, they said.

Speaking at his first set- piece White House press conference of the year, Mr Bush said he was "certain" the weapons were provided by the al-Quds force, a branch of Iran's elite Revolutionary Guards. But - like General Pace - he admitted he did not know if the order had come from the "top echelons" of the Islamic regime. However, he said: "My point is, what's worse, them ordering it and it happening, or them not ordering it and it happening?"

The President spoke as the House of Representatives embarked on a second day of debate on a resolution opposing the 21,500 troop "surge" in Iraq, currently being put into effect, amid US reports that the radical Shia leader Muqtada al-Sadr had left Iraq and was in Iran.

Given the majority Democrats' tight control of business on the House floor, the non-binding resolution is certain of passage in a vote set for tomorrow. But between 20 and 30 Republicans are expected to break ranks and back the motion - a sign of the strong public disapproval of the surge.

Mr Bush brushed off the likely setback, noting lawmakers had "every right" to oppose his Iraq policy. He focused instead on the upcoming House vote on further emergency funds for the war. "Our troops are counting on their elected leaders in Washington DC to provide them with the support they need to do their mission," he said.

That money will be approved, but further Congressional action is on the way. Nancy Pelosi, the Speaker, warned: "A vote of disapproval will set the stage for additional Iraq legislation which will be coming to the House floor."