WASHINGTON: The White House said on Monday that it would not negotiate with al Qaeda over the fate of an elderly US aid worker seized in Pakistan, after he made an emotional video plea to President Barack Obama.

“We cannot and will not negotiate with al Qaeda,” White House spokesman Jay Carney said, adding that officials were greatly concerned for the safety of the aid worker Warren Weinstein, and were working to find him.

On Sunday, Weinstein appeared in an al Qaeda video for the first time since he was kidnapped in Pakistan just days before he meant to return home in August.

The two-minute, 40-second video was posted on jihadist forums by al Qaeda's media arm as-Sahab, according to the US-based monitoring service SITE.

Dressed in a traditional Pakistani tunic and speaking impassively in English, he urged Obama to respond to his kidnappers' demands.

“If you accept the demands, I live; if you don't accept the demands, then I die,” he told the president in the video.

Weinstein, 70, suffers from asthma, heart problems and high blood pressure.

Al Qaeda leader Ayman al-Zawahiri has demanded that Washington end air strikes in Afghanistan, Pakistan, Somalia and Yemen, as well as release the 1993 World Trade Center bombers along with relatives of Osama bin Laden.