A Taliban leader who goes by the name Abu Yahya, just like American-turned-al Qaeda spokesman Adam Gadahn, was picked up in Karachi in recent days, but that person is not Gadahn, a senior Pakistani government official told ABC News.
Reports of the capture of an American-born al-Qaeda member by Pakistani authorities gave rise to speculation over whether it was Gadahn, the 31-year-old California-born Muslim convert who has been wanted since 2004.
The official told ABC News the leader who was arrested was possibly Abu Yahya Mujahdeen al-Adam, said to be another American member of al Qaeda, but the Pakistanis have yet to make that identification positive, the official said.
Dawn, an English-language newspaper, reports that Abu Yahya Mujahdeen al-Adam is an Egyptian-born U.S. citizen from Pennsylvania who helps command foreign militants fighting in Afghanistan and coordinates activities from Dubai.
The newspaper reports he is a close aide of Osama bin Laden and one of the "main financiers" of al Qaeda, and that he was arrested with the help of U.S. intelligence, and has been transported to Islamabad for interrogation.
Pakistani intelligence officials told ABC News that Karachi, the sprawling port city far from the Afghan border where Yahya was picked up, is where many other recent arrests have been made.
In the last six weeks, at least a half dozen senior Taliban commanders have been arrested, including the Afghan Taliban's military commander, two Afghan Taliban shadow governors and the son-in-law of Taliban chief Mullah Omar.
The word of an arrest of an American in Pakistan came just hours after the release of the lastest video of Gadahn, in which he praised Nidal Hasan, the U.S. Army major accused in the Fort Hood massacre last November.
"The Mujahid brother Nidal Hasan is a pioneer, a trailblazer and a role-model who has opened a door, lit a path and shown the way forward for every Muslim who finds himself among the unbelievers," Gadahn said in the video.
Gadahn grew up in southern California and converted to Islam. Officials say radical elements at an Orange County mosque convinced Gadahn to move to Pakistan. He has been there since 1998, attending al Qaeda training camp and becoming a leading voice for al Qaeda -- praising the attacks of Sept. 11, 2001, and today urging Muslims to launch more attacks against the United States.
"You shouldn't make the mistake of thinking that military bases are the only high-value targets in America and the West. On the contrary, there are countless other strategic places, institutions and installations which, by striking, the Muslim can do major damage to the crusader West," Gadahn said in the video.
Gadahn was charged with treason in 2006. He could face the death penalty if captured.