Osama bin Laden has criticised relief efforts in Pakistan and called for action against climate change in what appeared to be a new audio tape from the Al Qaeda leader.

The message marks the second time in a year that bin Laden has departed from his usual calls for armed attacks on the West to make a global theme such a natural disasters or economic crisis the centrepiece of a message.

It follows a statement in mid-September by Al Qaeda number two Ayman al-Zawahri also accusing the Pakistani government of reacting too slowly to the floods and a statement earlier this week by Al Qaeda spokesman Adam Gadahn on a similar theme.

The bin Laden message, about 11 minutes long, was broadcast with a video showing still images of bin Laden and images of natural disasters, the Islamist website used by Al Qaeda said.

The authenticity of the tape and its precise release date could not be immediately confirmed. However, bin Laden congratulates Muslims on the holy month of Ramadan, which started on August 11 and ended September 9.

He describes the fate of the Pakistani people following catastrophic floods, saying: "Millions of children are out in the open air, lacking basic elements of living, including drinking water, resulting in their bodies shedding liquids and subsequently their death."

Bin Laden also touches on global warming, the second time he is believed to have made climate change a prominent theme of one of his statements.

"The huge climate change is affecting our [Islamic] nation and is causing great catastrophes throughout the Islamic world," he says in the tape.

"It is not sufficient anymore to maintain the same relief efforts as previously, as it has become crucial to deliver tents, food and medicine."

Disasters exploited

Islamic charities, some with suspected ties to militant groups, were quicker than the Pakistani government to provide relief to flood victims.

Pakistani and US officials have repeatedly expressed concern that the Taliban and other militant groups could exploit the disarray to gain recruits.

Experts say South Asia is particularly vulnerable to climate change. A thaw of glaciers in the Himalayas could disrupt flows in rivers from the Ganges to the Yangtze, affecting hundreds of millions of people in Asia. Rising seas are also a big threat to densely populated low-lying areas of Bangladesh.

Noman Benotman, a former bin Laden associate who now works for Britain's Quilliam counter-extremism think-tank, said his use of a humanitarian message was a sign of desperation and showed the group was trying anything to gain popular support.

Al Qaeda has never pursued systematic humanitarian work during natural disasters of the kind carried out by aid organisations and Islamic relief charities, analysts say.

Australian counter-terrorism expert Leah Farrall described the statement as "hypocritical", noting that internal Al Qaeda documents found in Afghanistan and dated about 2000 commanded members not to be "distracted by relief and aid operations."

Bin Laden urged a big transformation in how relief work is executed, calling the number of victims of climate change much bigger than the victims of war.

The message was bin Laden's first since March 25, when he threatened to execute any Americans captured by Al Qaeda if accused September 11 mastermind Khalid Sheikh Mohammed was executed.

US soldiers and Afghan militia forces assaulted the Tora Bora mountains in 2001 after the September 11 attacks on the United States in pursuit of the Saudi-born bin Laden.

But he has never been found and is believed to be hiding in the mountainous border areas of Afghanistan and Pakistan.

- Reuters