'Ideologica terror'

"The time has come for you to liberate yourselves from fear and the ideological terrorism of neo-conservatives and the Israeli lobby," the voice says.

"The reason for our dispute with you is your support for your ally Israel, occupying our land in Palestine."

"I think it is very difficult to authenticate it [tape] properly"

Steve Park, terrorism and security analyst

Steve Park, a terrorism and security analyst in London, told Al Jazeera: "I think it is very difficult to authenticate it [tape] properly."

He said the Americans "have obviously thought there is some seriousness; that's why it has been released".

"I would imagine that they would be able to authenticate it through voice recognition relatively easily," said Park.

"We don't have a video, and one would imagine that the way al-Qaeda would be best able to get their message [across] is through a live video feed of Osama bin Laden.

"But obviously his whereabouts is still unknown although intelligence agencies would suggest that it is in the mountains between Pakistan and Afghanistan somewhere."

Obama 'powerless'

The release of the tape comes three days after the eighth anniversary of the September 11 attacks, carried out by al-Qaeda operatives, in which nearly 3,000 people died.

Bin Laden typically addresses the US in a message around September 11.

The 11-minute video shows a still picture of bin Laden while the audio of the address plays.

The voice says there has been little change in the White House under Obama and that Obama is "powerless" to stop the wars in Afghanistan and Iraq.

It also appears to refer to criticisms that Jimmy Carter, a former US president, made in June of Israel's Gaza war earlier this year.

The tape makes reference to Obama's speech in Cairo in June, suggesting the message was recorded afterwards.

The website where the message was posted had earlier said it would carry a "present" to Muslims from Bin Laden on the occasion of the holy month of Ramadan.

Bin Laden's last apparent message was issued just before Obama's speech, where the US leader talked of a "new beginning" between the US and the Muslim world.