US and Iraqi officials are still trying to confirm reports that the leader of al Qaeda in Iraq was killed by rivals north of Baghdad.
US authorities have urged caution and warned that even if the claim were true, the death of Abu Ayyub al- Masri would not spell the end of the terror movement in Iraq.
An al Qaeda-linked organisation gas denied that al- Masri, an Egyptian also known as Abu Hamza al-Muhajer, had been killed.
The Islamic State of Iraq said in a Web statement that al- Masri was "alive and still fighting the enemy of God".
However, the statement, posted on an extremist website, offered no evidence to support the claim. Al- Masri assumed leadership of al Qaeda after his predecessor, Abu Musab al-Zarqawi, was killed in a US airstrike last June.
Late yesterday, the leader of a Sunni Arab group opposed to al Qaeda told Iraqi television his fighters tracked down and killed al- Masri along with seven of his aides, two of them Saudis.
"Eyewitnesses confirmed his death and their corpses are still at the scene," said Abdul-Sattar al-Rishawi, head of the Anbar Salvation Council. Iraqi officials have released similar reports about the killing or capture of top insurgent figures, only to acknowledge later that the claims were inaccurate.
Reports of al-Masri's death first emerged from the Interior Ministry, which said the al Qaeda leader was gunned down by rivals in his movement yesterday at a bridge near Lake Tharthar just north of Baghdad, where the US military believes the group operates training camps.
Later, ministry spokesman Brig. Gen. Abdul-Karim Khalaf said al-Masri's death had not been confirmed. Another senior official, Maj. Gen. Hussein Kamal, said "we are trying to investigate and confirm the report".
Other Iraqi officials said word of the purported death came from an informant and that efforts were under way to retrieve the body.