“Several drone strikes have targeted al Qaeda positions in Nusab (in Shabwa province), killing nine members of the network,” a security source told AFP.

A tribal leader said soldiers of an unknown nationality were seen parachuting into the area and clashes ensued, suggesting it could be a new operation to try to free the US hostage.

al Qaeda in the Arabian Peninsula (AQAP) on Thursday threatened the imminent execution of US journalist Luke Somers who was kidnapped more than a year ago in Sanaa.

Yemen’s Al Qaeda branch publishes a video purporting to show an American hostage and threaten to kill him if their demands are not met.

Luke Somers, a 33-year-old photojournalist, was abducted in 2013 in Sanaa, the capital of Yemen, according to media reports. In a YouTube video published Wednesday, he says he is certain his "life is in danger."

The United States has said that American and Yemeni forces recently tried unsuccessfully to rescue Somers.

According to Yemen’s defence ministry, al Qaeda moved hostages, including the US journalist, a Briton and a South African, days before last month’s US-Yemeni raid in southeastern Hadramawt province.

Yemen is a key US ally in the fight against al Qaeda, allowing Washington to conduct a longstanding drone war against the group on its territory.

AQAP is considered by Washington as the most dangerous affiliate of al Qaeda.