Pakistani security agents denied on Monday that an American al Qaeda spokesman wanted in the United States for treason had been arrested, saying there had been confusion over the identity of a detained suspect.
Some Pakistani officials had said on Sunday that Adam Gadahn, a California-born convert to Islam with a $1 million US bounty on his head, had been arrested on the outskirts of the city of Karachi.
But a senior government official and two security agents said on Monday the suspected al Qaeda operative picked up in Karachi was not Gadahn.
"Our initial impression was that the guy was Adam Gadahn but that information now looks incorrect," said one security official, who declined to be identified.
The arrested man was believed to be an American who goes by the alias Abu Yahya, the officials said. Gadahn is known to have used a similar alias.
"Probably the name and his origin caused the confusion," the first official said.
He declined to speculate about the identity of the arrested man except to say he was apparently an American al Qaeda operative.
"We don't know yet how big a catch he is," he said.
Pakistan is battling indigenous, al Qaeda-linked Taliban militants and has resisted US pressure to launch military offensives against Afghan Taliban factions based in rugged ethnic Pashtun lands on its northwestern border.
While ruling out another big offensive soon, Pakistan has arrested several senior members of the Afghan Taliban in recent weeks, including a top military commander, Mullah Abdul Ghani Baradar.
But Islamabad, apparently nervous of a public backlash in a country where anti-US feeling runs high, has only officially confirmed Baradar's arrest.
Gadahn has been involved with al Qaeda's as-Sahab media wing and has appeared in al Qaeda videos wearing robes and a turban and warning the United States that it would face attacks if it did not heed al Qaeda demands.
On Sunday, a video was released on Islamist websites in which Gadahn called for Muslims in the United States to launch attacks to undermine the economy, according to a website that monitors al Qaeda announcements.
The FBI has been seeking to question Gadahn since May 2004, and the US government has offered up to $1 million in reward money for information leading to his arrest.
The 2006 treason charge against him carries a maximum punishment of death.
Separately, a senior Pakistani Taliban commander linked with al Qaeda who the government said last week may have been killed in a Pakistani air raid telephoned a Reuters reporter to say he was alive.
Interior Minister Rehman Malik said on Saturday senior Pakistani Taliban commander Faqir Mohammad may have been among 16 insurgents killed when helicopter gunships attacked a militant hideout in the Mohmand region on Friday.
"I'm fine. It's just propaganda," said the man on the telephone who identified himself as Mohammad. The reporter has spoken to Mohammad before and said he recognised his voice.
"I was in Bajaur, not Mohmand that day. None of our commanders were killed in the attack. We lost some fighters and women," the man purporting to be Mohammad said, referring to another region on the Afghan border.