An air strike has killed a top al-Qaeda leader on the FBI's most wanted list for his role in the 2000 bombing of the USS Cole warship, Yemeni officials said.
The air strike resembled earlier US drone attacks, but the US did not immediately confirm it.
Fahd al-Quso was hit by a missile as he stepped out of his vehicle, along with another al-Qaeda operative in the southern Shabwa province, Yemeni military officials said. They were speaking on condition of anonymity in accordance with military regulations.
Al-Quso, 37, was on the FBI's most wanted list, with a $US5 million ($4.9 million) reward for information leading to his capture. He was indicted in the US for his role in the 2000 bombing in the USS Cole in Aden, Yemen, in which 17 American sailors were killed and 39 injured.
He served more than five years in a Yemeni prison for his role in the attack and was released in 2007.
A telephone text message claiming to be from al-Qaeda's media arm confirmed al-Quso was killed in the strike.
Al-Quso was also one of the most senior al-Qaeda leaders publicly linked to the 2009 Christmas airliner attack. He allegedly met the suspected bomber, Umar Farouk Abdulmutallab, in Yemen before he left on his way to execute his failed bombing over Detroit.
In December 2010, al-Quso was designated a global terrorist by the US State Department, an indication that his role in al-Qaeda's Yemen branch had grown more prominent.
Local Yemeni official Abu Bakr bin Farid and the Yemeni embassy in Washington confirmed al-Quso was killed in Rafd, a remote mountain valley in Shabwa. It is the area where many al-Qaeda leaders are believed to have taken cover, including the US-born cleric Anwar al-Awlaki, killed in a US air strike in Yemen last year.
Al-Quso was from the same tribe as al-Awlaki.
The State Department had no immediate comment.
Yemen's government has been waging an offensive on al-Qaeda militants, who have taken advantage of the country's political turmoil over the last year to expand their hold in the south.
The new Yemeni President has promised improved co-operation with the US to combat the militants. On Saturday, he said the fight against al-Qaeda was in its early stages.
Al-Quso's association with al-Qaeda dated back more than a decade, when he met Osama bin Laden in Afghanistan. Bin Laden allegedly told him to "eliminate the infidels from the Arabian Peninsula".
From there he rose through the ranks. He was assigned in Aden to videotape the 1998 suicide bombing of the USS Cole, but he fell asleep.
Despite the lapse, he became a mid-level manager.