In this Oct. 11, 2006 file photo, a wanted poster of Adam Yahiye Gadahn is displayed at the Justice Department in Washington.

KARACHI: An American captured in Pakistan this week and accused of being a key spokesman for al-Qaeda was wrongly identified as Adam Gadahn, the most wanted American in the terrorist organisation, Pakistani officials admitted today.

The man arrested in the southern city of Karachi was first identified as Mr Gadahn, who was born in Oregon and is considered a major al-Qaeda figure because of his success in recruiting English-speaking converts to jihad. However, Pakistani authorities have now admitted that it was a case of mistaken identity and they have a different American in custody.

The name of the man who was detained on Saturday is Abu Yahya Majadin Adam, which is similar to one listed on the FBI’s website as an alias for Mr Gadahn, 31, who has appeared in several al-Qaeda videotapes threatening the West since 2001.

“The resemblance of the name initially caused confusion, but now they have concluded he is not Gadahn,” an unnamed intelligence officer said.

“He feels proud to be a member of al-Qaeda,” the officer added.

Word of the arrested man’s real identity came on the same day that a suicide car bomber struck a police intelligence building in the eastern city of Lahore, killing 13 people. The attack broke what had been a relative lull in violence in Pakistan, and demonstrated that militant groups are still capable of carrying out attacks on key targets, despite coming under increasing pressure from Pakistani military operations and CIA drone attacks.

A senior US military intelligence official confirmed that the man arrested does not appear to be Mr Gadahn.

Bill Burton, a White House spokesman, said that President Obama was getting updates on reports of the detained American but that the White House had not confirmed the information.

Rehman Malik, the Pakistani Interior Minister, cited unspecified reports that: some foreigners were arrested “two days back”.

He said he had asked for more information on their identities from the intelligence agencies.

Rick Snelsire, a spokesman for the US Embassy, said that the Embassy had not been informed of any Americans being arrested, raising further questions about the man in custody.

The last known American al-Qaeda member to be arrested in Pakistan was Bryant Neal Vinas, who was captured by Pakistani authorities in late 2008 in the northwestern city of Peshawar near the Afghan border.

Several other Americans are known to have gone to Pakistan to join militants, including John Walker Lindh, now imprisoned, and Jose Padilla, who was convicted of sending money, recruits and supplies to Islamic extremist groups.

Pakistani police arrested five young American Muslims in December in Sarghoda who they allege were trying to link up with militants. The men could face charges of waging war against Pakistan and planning terrorist attacks in the country.