Said al-Shihri, described as the second-in-command of al-Qaeda in the Arabian Peninsula (AQAP), has been killed in an operation in southern Yemen, government officials say.
Al-Shihri was reportedly killed with six others in the Hadramawt area.
Some reports say Yemeni troops were involved, others that it was an air strike, possibly a US drone attack.
Al-Shihri, a Saudi national, was released by the US from detention in Guantanamo Bay in 2007.
Yemen has previously announced it had killed al-Shihri and his death this time has not been confirmed.
The Yemeni army has been fighting Islamist militants in the south of the country for months.