THE Prime Minister warned Iran last night against interfering in Iraq and told it to cease all support for terrorist groups and to co-operate with nuclear weapons inspectors.

Speaking on the eve of his visit to Iraq, Tony Blair hardened his position amid fears that religious fundamentalists were trying to influence the shape of the future government of Iraq. America has accused Iran of trying to develop nuclear weapons, and intelligence chiefs suspect that it is harbouring al-Qaeda terrorists involved in the Riyadh suicide bombings.

Mr Blair, who will thank British troops today for their part in toppling Saddam Hussein, is expected to urge Iraqi leaders to move swiftly to democratic government to prevent outside interference. Britain and America had found since the war that Iraqis of all religious denominations wanted to be in charge of their own country without outside interference from anyone, he said. That was why a proper government in Iraq should be run by the Iraqi people.

The British Government, and particularly Jack Straw, have been working in recent years to build a closer relationship with Iran. But Mr Blair’s remarks suggest that he may be losing patience. Britain had established a dialogue with Iran “which we value”, but he added: “This has to be on the basis of honest talking about what is acceptable and not acceptable.”

His words remained more cautious than recent American statements on Iran, but they brought him much closer to the White House position. Senior American officials are meeting today in the White House to work out a more clearly defined policy. Intelligence reports that al-Qaeda operatives based in Tehran were behind the Riyadh bombings have prompted Pentagon officials to press the White House to adopt a more aggressive approach, which could involve covert efforts to destabilise the ruling Iranian clerics.

Donald Rumsfeld, the US Defence Secretary, warned Iran on Tuesday that America would “aggressively put down” any attempt to install a theocratic regime in Iraq. Shia Muslim clerics with close theological or political ties with Iran are believed to have been emerging as potential Iraqi leaders.

The Bush Administration pulled out of a meeting with Iranian officials in Geneva last week in protest at what the US alleged was the Islamic Republic’s harbouring of terrorists and it has sharpened its accusations that Iran was developing nuclear weapons.

Last night Condoleezza Rice, Mr Bush’s National Security Adviser, expressed deep concern “about what is going on in Iran”, particularly its nuclear ambitions, and said she expected the International Atomic Energy Agency to rule next week that Iran was poised to equip itself with nuclear weapons technology. The agency is due to report on whether it believes Iran’s nuclear plants are purely peaceful, but Dr Rice said: “We believe that the IAEA will demonstrate that there is indeed a problem that needs to be dealt with.”

Mr Blair said that it was important that Iran co-operated with the agency’s inquiries and that it did not support al-Qaeda or any other terrorist group, particularly with the Middle East peace process at a vital stage. A “frank conversation” was needed about the problems that had been identified.

“I think that the White House is expressing concerns about nuclear weapons,” he said. “There are concerns. Those concerns are not invented in the sense that there is no basis for them. It is difficult to know what is the case and what is not, which is why we must have a proper dialogue.” The energy authority must be allowed to do its work properly and discover “what the nature of this programme is”.

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