Afghan warlord Gulbuddin Hekmatyar says that he is ready to fight under the banner of al-Qaeda, according to a video broadcast by al-Jazeera TV.
Hekmatyar opposes Hamid Karzai's government
"We hope to participate with them in a battle that they lead. They hold the banner and we stand alongside them as supporters," he said in the video.
The rebel warlord is classified as a terrorist by the United States.
He is opposed to the central government of Hamid Karzai and urges war against foreign troops in Afghanistan.
Mr Hekmatyar was Afghanistan's prime minister from June 1993 to June 1994. His faction, the Hezb-e-Islami, helped end the Soviet occupation of Afghanistan.
Berates the West
In the video, a bearded Gulbuddin Hekmatyar wears a black turban and has a machine gun propped up against the wall behind him.
He berates Western governments for not taking seriously a truce offer made by Osama Bin Laden in January to the American people and another to European countries in April 2004.
"The Americans and their friends the Europeans are the ones who declared war on the Muslims and ignited the flames in Palestine, Afghanistan and Iraq," he says.
"They are trying to rule Muslim states directly or through their vassals. They are plundering the wealth of Muslims and holding them back from self determination."
His group has been blamed for several recent attacks against US-led coalition forces in Afghanistan.
Correspondents say that statements from Gulbuddin Hekmatyar are rare, but when they appear, their theme and tone is the same: hatred of the United States and its allies in Afghanistan and calls for rebellion there in the name of Islam.