An audiotape attributed to Abu Musab al-Zarqawi, the most wanted man in Iraq, has surfaced on an Islamist website claiming that he is only "lightly wounded".

The tape emerged after a week of speculation about the health of the man Osama bin Laden has identified as his deputy, which began when rebels posted a message on the internet asking those loyal to the insurgency to pray for his health.

Today has already been a turbulent day in Iraq as four US troops, four Italians and one Iraqi pilot died in separate air crashes and Operation Lightning, a huge operation aimed at securing the streets of Baghdad, entered its third day.

The message could not be immediately authenticated. On it, the voice claiming to be al-Zarqawi dismissed stories that he had been incapacitated. "I think news has reached your ears through the media that I was seriously wounded... I would like to assure you and assure Muslims that these are baseless rumours and that my wounds are minor," it says.

The tape is dated May 27. It does not reveal any details about al-Zarqawi’s injuries but it does mention fierce fighting around the city of al Qaim in northeast Iraq.

Last week there were conflicting reports on Islamist websites, some claiming that al-Zarqawi was wounded and had handed over control of his group to a deputy and others insisting that the Jordanian-born extremist was leading a response to police operations in Baghdad.

On Sunday, General Richard Myers, the outgoing chairman of the US Joint Chiefs of Staff, said America "tends to believe" that al-Zarqawi was wounded during Operation Matador, which was aimed at capturing him, on the Iraq-Syria border earlier this month.

Al-Zarqawi already has only one leg after being hit by a United States missile in Afghanistan in 2002. With a $25 million bounty on his head, has been the most eagerly sought leader of the Iraqi insurgency since Saddam Hussein was captured in December 2003.

The speaker on the tape said that al-Zarqawi was continuing his fight "against the Crusaders and the enemies of religion" despite his injuries, and that "the enemy today is living out his worst days in Iraq". The tape also criticised Iraq’s Shia Muslims and their spiritual leader, Ayatollah Ali al-Sistani, who is described as a "cleric of atheism" for his support of the American-led occupation.

Elsewhere in Iraq, one of the seven aircraft used by the Iraqi Air Force for surveillance and personnel transport crashed after leaving Kirkuk air base, killing four US Air Force members and an Iraqi pilot, according to a United States military spokesman. Last night, an Italian military helicopter also crashed, killing its two pilots and two gunmen about 13 kilometers (eight miles) southeast of Nasiriyah.

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