A US hostage held by the Al-Qaeda group has been killed during a rescue operation in Yemen's southern Shabwah province, a senior Yemeni security source said Saturday.
"Luke Somers was killed during a military operation to rescue him in Nisab town," the source, requesting anonymity, told Anadolu Agency.
The source, however, declined to give further details.
A military source earlier told the Yemeni Defense Ministry's website that Somers had been freed during the operation.
His sister, however, told the Associated Press that her brother had been killed during a failed attempt to free him.
Somers, 33, has been abducted by the Al-Qaeda group in September 2013 in Yemeni capital Sanaa.
On Thursday, the Al-Qaeda group threatened to kill Somers within three days unless Washington meets its demands, which the group did not outline.
The group said in a video on Thursday that it will kill Somers, 33, within three days if the US failed to give into its demands.
The group released a video of the US hostage, in which urged US authorities to intervene to rescue him.
The Yemeni government says Al-Qaeda remains active in several parts of the country's south, from which it stages sporadic attacks on army and police personnel.
Yemen has been dogged by turmoil since pro-democracy protests forced president Ali Abdullah Saleh to step down in 2012 after 33 years in office.