Osama bin Laden has reiterated a call for aid to flood victims in Pakistan, in the second such audio message posted online in as many days, a US monitoring group said on Saturday.

In a speech entitled "Help Your Pakistani Brothers," the Al-Qaeda leader focuses on the reluctance of Arab and Muslim countries to help Pakistanis, singling out Gulf states, Malaysia and Turkey, SITE Intelligence Group said.

"The response did not match the level of the disaster," said the voice whose authenticity could not be immediately verified.

Bin Laden said Arab and Muslim leaders had not paid any visits to flood-hit areas unlike UN chief Ban Ki-moon, and added Arabian Peninsula oil wealth should be used as it "belongs to all Muslims."

The 13-minute recording appeared on the Internet around 24 hours after bin Laden expressed concern about global climate change and flooding in Pakistan in a similar audio message aired on the Internet.

"The number of victims caused by climate change is very big... bigger than the victims of wars," bin Laden said in Friday's tape, which would have been the first time he had spoken publicly since March 25.

Paul Pillar, a former top US intelligence official, said that that message by bin Laden was aimed at polishing his battered image among Muslims.

He aims "to counteract his loss of support among people who have come to perceive him as an uncaring terrorist who has no hesitation about spilling the blood even of fellow Muslims," Pillar told AFP.

Bin Laden's whereabouts are unknown, but in August, the US commander in Afghanistan, General David Petraeus, said he is "far buried" in the remote mountains between Afghanistan and Pakistan and that capturing him remains a key task.