Ahmad Chalabi, the former Iraqi exile most closely identified with the US decision to go to war in Iraq, was received on Wednesday at the top of the Bush administration in a sign that the secular politician is perceived once again by Washington as someone to do business with after his spectacular fall from grace last year.

But Democrats in Congress demanded that Mr Chalabi, now a deputy prime minister with special responsibility for the oil iindustry, appear before them to answer questions on his role in the pre-war intelligence that was used to justify the invasion. Senators also wanted to know the status of a reported FBI investigation into allegations that Mr Chalabi passed intelligence to Iran.

For Mr Chalabi, returning to the Washington limelight for the first time in over two years was a moment to be relished as he stood before television cameras and an applauding audience to address the American Enterprise Institute (AEI).

“Iraq is now at the threshold of a new era,” he said, then added: “We are not out of the storm.”

Mr Chalabi introduced members of the new secular coalition he has formed to contest parliamentary elections on December 15, breaking away from the Shia Islamic alliance that helped propel him into office following last January’s polls.

Asked if he harboured ambitions to become prime minister, he joked: “That’s for me to know and you to find out.”

Administration officials, however, were less keen on publicity on Wednesday. In a break with normal practice, cameras were excluded from his meeting with Condoleezza Rice, secretary of state. Mr Chalabi, a former banker who has been convicted by a court in Jordan, also met Dick Cheney, the vice president, and Stephen Hadley, national security advisor.

Analysts assessed it would be wrong to say that Mr Chalabi had undergone a wholesale political rehabilitation within the administration.

However, they said, some influential figures in Washington saw Mr Chalabi as an important secular politician who had cultivated a relationship with Grand Ayatollah Ali Sistani, the most influential Shia cleric.

Even before the 2003 invasion, the Bush administration was seriously divided over the merits of backing Mr Chalabi and his fellow exiles.

While he had his mentors in the Pentagon - who flew him into occupied southern Iraq soon after the invasion -- the State Department had long preferred his rival, Iyad Allawi. And the CIA was suspicious of the sources and defectors produced by Mr Chalabi’s Iraqi National Congress.

According to the Robb-Silberman Commission that looked into US intelligence on weapons of mass destruction, the CIA concluded that two sources provided by the INC had fabricated information about Iraq’s alleged mobile biological warfare units and the possible construction of a new nuclear facility.

But the commission also concluded that, according to the CIA’s post-war investigations, the “INC-related sources had a minimal impact on pre-war assessments”, although some of the erroneous information ended up by mistake in then secretary of state Colin Powell’s presentation to the United Nations in February 2003.

Nonetheless, Mr Chalabi’s hosts on Wednesday at AEI , the influential neoconservative policy group, had long backed his cause -- even after the events of early 2004 when the Pentagon stopped funding his party, his Baghdad offices were raided by police with the blessing of Paul Bremer, the US governor, and he was excluded from the caretaker government led by Mr Allawi after anonymous US officials accused him of spying for Iran.

Peppered with questions by reporters on Wednesday, Mr Chalabi denied he had ever passed classified information to Iran, or provided fabricated evidence on WMD to the Bush administration. That was “an urban myth” he said, and repeatedly urged reporters to read the Robb-Silberman report which he claimed had exonerated him.

Mr Chalabi’s appearance in Washington, while at the invitation of the Bush administration, has come at a sensitive time, coinciding with the president’s slide in opinion polls and renewed calls for probes into the use of pre-war intelligence in the wake of the indictment of the vice president’s chief of staff, Lewis Libby, for lying to a special prosecutor.

Explaining the visit of such a controversial politician, Scott McClellan, the White House spokesman, commented:

“Deputy Prime Minister Chalabi is one of a number of elected leaders who have visited Washington in recent months, and we believe it’s very important to work closely with the Iraqi government and their leaders to advance democracy, build prosperity, and improve security for the Iraqi people.”

Adel Abdul Mahdi, an Iraqi vice president, is also in Washington this week.

Senator Richard Durbin, an Illinois Democrat, was incensed with the visit by Mr Chalabi.

“Here we have a man accused of selling secrets to the enemy, to Iran, and endangering American troops and where do we find Ahmad Chalabi today? He is being hosted and feted by this administration,” he said in a speech to the Senate on Tuesday.

Henry Waxman, the senior Democrat on a House subcommittee for national security, called for Mr Chalabi to answer questions under oath before the House government reform committee which planned to meet privately with him on Wednesday.

Mr Chalabi told reporters he would be glad to answer questions before Congress, but an associate suggested that this was not likely to happen under oath and in front of cameras.