Al Qaida claimed responsibility for the kidnapping of a Jewish American man who has gone missing Pakistan, the group's leader said on Thursday, citing a lifting of Israel's "siege" of the Gaza Strip as one condition toward securing the man's release.

In an audio recording issued on Islamist websites, Al-Qaida leader Ayman al-Zawahri claimed that the militant group had abducted Warren Weinstein, an American development expert, in the Pakistani city of Lahore in August.

Weinstein, about 70 years old, had been working on a project in Pakistan's northwestern tribal areas where Pakistani troops have been battling Islamist insurgents for years.

In exchange for Weinstein's release, an ABC report claimed, Zawahiri requests the lifting of the Israeli "siege" of the Gaza strip, the complete end of "bombings by America and its allies in Pakistan, Afghanistan, Yemen, Somalia and Gaza," as well as the release of all Al-Qaida and Taliban prisoners.

"I tell the captive soldiers of Al-Qaida and the Taliban and our female prisoners held in the prisons of the crusaders and their collaborators, we have not forgotten you and in order to free you we have taken hostage the Jewish American Warren Weinstein," says Zawahiri in the 30-minute statement.

Addressing Weinstein's family, the Al-Qaida official said: "Your problem is not with us but with [U.S. President Barack] Obama. We have raised fair demands ... So continue to pressure Obama, if you want your relative to be handed back."

Zawahri said that Attiyatullah, a Libyan militant whose real name was Jamal Ibrahim Ashtiwi al-Misrati, had escaped a first air strike but was killed along with his son Issam in a second bombing on August 23.

"He was martyred, may God have mercy on him ... by bombing by a crusader spy plane," Zawahri said.

Zawahri was named by the Islamist group to succeed Osama bin Laden who was killed in an operation by U.S. forces in Pakistan in May after a decade-long worldwide hunt.

Al-Qaida has tried to wage war on Arab rulers over the past decade through creating cells that used suicide attacks on foreigners and government installations and officials.
But the Arab Spring popular uprisings have left Al-Qaida on the sidelines, as uprisings brought down veteran heads of state in Egypt, Tunisia, Libya and Yemen.