AP:

KARACHI, Pakistan – The American-born spokesman for al-Qaida has been arrested by Pakistani intelligence officers in the southern city of Karachi, two officers and a government official said Sunday, the same day Adam Gadahn appeared in a video urging U.S. Muslims to attack their own country.

The arrest of Gadahn is a major victory in the U.S.-led battle against al-Qaida and will be taken as a sign that Pakistan, criticized in the past for being an untrustworthy ally, is cooperating more fully with Washington. It follows the recent detentions of several Afghan Taliban commanders in Karachi, including the movement's No. 2 commander.

Gadahn has appeared in more than half a dozen al-Qaida videos, taunting and threatening the West and calling for its destruction. A U.S. court charged Gadahn with treason in 2006, making him the first American to face such a charge in more than 50 years.

He was arrested in the sprawling southern metropolis of Karachi in recent days, two officers who took part in the operation said. A senior government official also confirmed the arrest, but said it happened Sunday. The discrepancy could not immediately be resolved.

They spoke on condition of anonymity because they were not authorized to release the information.

The intelligence officials said Gadahn was being interrogated by Pakistani officials. Pakistani agents and those from the CIA work closely on some operations in Pakistan, but it was not clear if any Americans were involved in the operation or questioning.

In the past, Pakistan has handed over some al-Qaida suspects arrested on its soil to the United States.

Gadahn grew up on a goat farm in Riverside County, California, and converted to Islam at a mosque in nearby Orange County.

UPDATE: It's looking like the man they arrested is not Gadahn.