An audio message purportedly from Al-Qaeda leader Osama bin Laden has praised an attempted bombing of an American airliner near Detroit on Christmas Day.
The voice on the tape, broadcast on Al-Jazeera television, warned of further attacks.
The recording says that the message is from "Osama to Obama". The BBC reports the authenticity of the tape has not been verified. But Al Jazeera says the voice is that of bin Laden.
It is nearly seven months since the last audio message from Osama bin Laden.
A White House adviser says it remains unclear whether the claim of responsibility is valid.
Yemeni officials have said the Detroit plane suspect met Al-Qaeda leaders when he visited Yemen.
Umar Farouk Abdulmutallab, 23, has been charged with attempting to blow up a Delta Airlines plane as it approached Detroit from Amsterdam on Christmas Day. A bomb hidden in his underwear failed to explode.
He pleaded not guilty in a Detroit court on 9 January.
In September, a 10-minute audio tape from al-Qaeda warned President Barack Obama he was "powerless" to stop the wars in Iraq and Afghanistan.
Another audio tape in June last year accused Mr Obama of fuelling hatred of America in Pakistan.
