Abu Musab al-Zarqawi, the most wanted man in the Middle East, may have been killed in a firefight in Iraq, according to the country's Foreign Minister.
Hoshyar Zebari said that urgent DNA tests were being carried out on the bodies of several people who died when US and Iraqi forces stormed a house in the northern city of Mosul.
The US administration, which had offered a US$25m reward for the leader of al Qaeda in Iraq, played down the reports.
But Mr Zebari, during a visit to Moscow, said: "American and Iraqi forces are investigating the possibility that Abu Musab al-Zarqawi's corpse is among the bodies of some terrorists who died in the special military operation in Mosul."
State television in Jordan, where 59 people died in a series of hotel bombings for which Zarqawi's group has claimed responsibility, carried the alleged death as "urgent news" in a scrolling newsbar at the bottom of the screen, suggesting that Jordanian officials believe the report to be credible.
Eight fighters, supposedly senior members of the group al Qaeda in Iraq, died after special forces and other soldiers surrounded a house following a surveillance operation.
Four of them were killed during a three-hour assault on the two-storey building.
The rest blew themselves up.
One of the dead was a woman with the words "suicide bomber" marked on her chest.
The operation, in which two US soldiers were also killed, was reminiscent of one carried out by US forces when they killed Saddam Hussein's sons, Uday and Qusay.
It took place after a tip off that Zarqawi was at the house.
Brigadier General Said Ahmed al-Jabouri, of the Iraqi army, said that the information came from a credible source.
Zalmay Khalilzad, the US ambassador to Iraq, said: "I do not believe that we got him.
But his days are numbered.
We're closer to that goal but unfortunately we didn't get him in Mosul." In Washington, Trent Duffy, a White House spokesman, added that reports of Zarqawi's death were "highly unlikely and not credible".
Zarqawi's group had claimed responsibility for some of the conflict's most spectacular attacks.
The Sunni extremists have also kidnapped and beheaded a number of foreign hostages.
Zarqawi is beginning to rival Osama bin Laden as America's public enemy number one.
But many Iraqis believed his group has claimed credit, or had been credited with by the US, a far more important role in the insurgency than was the case.
A leading member of the Sunni Association of Muslim Scholars was also killed yesterday outside his home in Basra, in the British-controlled south.
Khalil Ibrahim had been among members of the association who had been repeatedly critical of the Shia-dominated government in Baghdad.
Meanwhile, an Iraqi reconciliation conference being held in Cairo agreed that there should be a timetable for the withdrawal of foreign troops and resistance against foreign occupation was justified.
A final statement said that acts of terrorism should be condemned.
The Interior Minister, Bayan Jabr, said that Iraqi troops would be ready to take charge of security in the country by the end of next year.