A new audio message purportedly belonging to Osama bin Laden praises Abu Musab al-Zarqawi and claims the recently slain leader of al Qaeda in Iraq was under orders to target attacks against Iraqis who support the U.S. forces.

Bin Laden also vowed further attacks against the U.S. and demanded al-Zarqawi's body be returned to his family.

The audio message, which was posted on an Islamic web forum, was accompanied by a still image of bin Laden and pictures of al-Zarqawi taken from videos that were released earlier.

Hours after Friday's message appeared, the same website placed an ad saying bin Laden would soon issue another tape directed to "the Islamic nation in general and the mujahedeen in Iraq and Somalia in particular."

A similar advertisement was posted about 24 hours before bin Laden's latest message was posted early Friday.

In Friday's 19-minute audio message -- apparently the fourth from bin Laden this year -- the leader of al Qaeda sounded winded and tired at times as he described al-Zarqawi as a martyr and the "lion of holy war."

"Al-Zarqawi's story will live forever with the stories of the nobles, so don't cry over one who is not missing," bin Laden said. "He can teach the world a lesson on how to seize freedom ... and how to resist tyrants."

However his comments towards the U.S. were no less vitriolic than in the past.

"We will continue to fight you and your allies everywhere, in Iraq, Afghanistan, Somalia and Sudan to run down your resources and kill your men until you return defeated to your nation," bin Laden said, apparently speaking directly to U.S. President George Bush.

Bin Laden is thought to have released three other audio messages this year. Though the voice on the new tape has not yet been confirmed as bin Laden's, it is said to resemble the voice on the earlier messages.

Terrorism expert Eric Margolis told CTV's Canada AM the tape is intended to inspire the insurgency.

"There are two interesting points in the tape. First of all, he said that, quote, we're going to continue to bleed the United States financially in money and men. And that has long been bin Laden's strategy. He knows he can't win by military action, but he thinks he can push the U.S. out of the Middle East by hurting it financially," Margolis said.

"Secondly he said we're expanding the struggle not only to the Middle East but to Sudan and Somalia."

Margolis said bin Laden's warm tribute to al-Zarqawi rings hollow, because he was often critical of his brutal tactics while he was still alive.

Al-Zarqawi was killed in a U.S. airstrike on June 7 northeast of Baghdad.

"(The comments) are probably designed to encourage the jihadists, the anti-American movement, rather than really to memorialize his memory," Margolis said.

In the tape, bin Laden plays down claims that al-Zarqawi is responsible for a series of suicide bombings against Shiite Muslims in Iraq.

"Abu Musab had clear instructions to focus his fight on the occupiers, particularly the Americans and to leave aside anyone who remains neutral," bin Laden says on the audio tape.

"But for those who refused (neutrality) and stood to fight on the side of the crusaders against the Muslims, then he should kill them whoever they are, regardless of their sect or tribe. For supporting infidels against Muslims is a major sin," bin Laden said.

One week ago the deputy leader of al Qaeda, Ayman al-Zawahri, issued his own tribute to al-Zarqawi.

But before his death, bin Laden and al-Zawahri criticized al-Zarqawi's brutal methods, claiming they tarnished the terror-organization's reputation.

In the tape, bin Laden also calls on the U.S. to return the body, and urges King Abdullah II of Jordan to allow al-Zarqawi's family to bury his remains.

"What scares you about Abu Musab after he's dead?" bin Laden said, addressing Abdullah. "You know that his funeral, if allowed to happen, would be a huge funeral showing the extent of sympathy with the mujahedeen."

Bin Laden and al-Zawahri are thought to be hiding in the mountainous, remote border zone of Pakistan and Afghanistan.

The message carried the logo of As-Sahab -- the video production arm of al Qaeda.

With files from The Associated Press