Arabic television channel al-Jazeera has broadcast an audiotape purportedly from Saddam Hussein's former deputy Izzat Ibrahim al-Douri.
Izzat Ibrahim al-Douri was one of Saddam Hussein's inner circle
The voice on the tape urges Arab leaders due to meet in Sudan to boycott the Iraqi government and recognise what he calls the "Iraqi resistance".
The speaker also condemns recent attacks on Shia shrines in Iraq.
There had been persistent speculation about whether Mr Douri, one of Iraq's most wanted men, was dead or alive.
A number of websites linked to the former ruling Baath party reported last November that Mr Douri had died of cancer.
Expel the representatives of collusion and treason who have sold their religion and homeland at the cheapest prise
But the US military - which has offered a reward of up to $10m for information leading to Mr Douri's capture - said at the time that it was treating those claims with caution.
The tape broadcast by al-Jazeera has yet to be authenticated and no date has been given for the recording.
The speaker calls on leaders taking part in the Arab League summit on Tuesday to "boycott the regime of agents and traitors", saying the current Iraqi government was "appointed by the US occupiers".
The US has offered a reward of up to $10m for Mr Douri's capture
He also urges them to recognise the "Iraqi resistance as the sole legitimate representative of the Iraqi people".
The voice also describes recent attacks on Shia mosques and holy sites, which have sparked widespread sectarian violence, as a "crime".
Mr Douri has been accused of financing Sunni insurgent groups in Iraq.
The 63-year-old was the second most powerful man in Saddam Hussein's Iraq and is regarded by the US as their most wanted man after the leader of al-Qaeda in Iraq, Abu Musab al-Zarqawi.
He was number six on the US list of 55 most-wanted members of Saddam Hussein's regime. The top five have been captured or killed.
Mr Douri was diagnosed with leukaemia several years ago but recovered. He often represented Iraq at foreign gatherings - most markedly in the run-up to the US-led invasion of April 2003.
Considered Saddam Hussein's right-hand man, he was deputy commander-in-chief of the armed forces and held a senior post on the committee responsible for northern Iraq when chemical weapons were used in 1988, killing thousands of Kurds at Halabja.
He served as vice-chairman of the Revolutionary Command Council and was a key commander in the suppression of the failed Shia uprising in 1991.
He went into hiding after the US-led invasion in 2003.