In an audiotape aired on an Islamist website, the speaker said to be bin Laden paid a glowing tribute to Zarqawi, the most wanted man in Iraq who was killed in a US air strike on his hideout three weeks ago.

He described the Jordanian-born Zarqawi as "a lion of Islam and jihad who does honor not just to his family and tribe but to the whole of mankind."

"We will keep up our fight to bleed your money dry, kill your men and so that (your forces) go home defeated, as we defeated you in Somalia," bin Laden told US President George W. Bush.

"Don't rejoice too much. The banner (of jihad) has not fallen. It will be picked up by another lion of Islam. We will continue our fight against you everywhere, in Iraq, in Afghanistan, in Somalia and in Sudan."

Zarqawi, who orchestrated a bloody campaign of attacks and beheadings of hostages, had long remained elusive in Iraq despite a 25-million-dollar US bounty on his head until his killing on June 7.

Bin Laden defended Zarqawi against critics who attacked him for killing Iraqis, chiefly Shiite Muslims who were long oppressed under ousted dictator Saddam Hussein, and not just US-led forces which invaded in March 2003.

"(Zarqawi) had clear instructions to concentrate his fight on the occupying invaders, chiefly the Americans, and to spare all those who opted for neutrality," the voice said in the tape, which could not be authenticated.