US jets carried out dozens of airstrikes on Al-Qaeda targets in Yemen overnight and in the past 48 hours in one of the lengthiest, sustained operations inside the conflict-torn Arab country, Yemeni officials and residents said Friday.

According to the officials, the strikes focused on a triangle-shaped mountainous region where three Yemeni provinces meet: Bayda, Shabwa, and Abyan.

Casualty figures have been slow to emerge but officials said seven alleged al-Qaeda militants were killed in the strikes on Thursday.

A senior Yemeni official described the strikes as 'open-ended' and said they raised questions about the objectives of such an operation.

According to Yemeni officials, the strikes focused on a triangle-shaped mountainous region where three Yemeni provinces meet: Bayda, Shabwa, and Abyan

Residents in Shabwa said the strikes hit the town of Wadi Yabsham, where Saad Atef, the No. 2 figure in Yemen's Al-Qaeda branch, is living.

The residents and officials spoke on condition of anonymity because they weren't authorized to talk to journalists.

Sadek al-Jaouf, a Bayada tribal leader, told The Associated Press that houses were bombed in Yakla district - the site of a US special operations' raid two months ago in which a Navy SEAL was killed, six American soldiers were wounded and a US military aircraft suffered a hard landing and had to be destroyed.

In the ground operation, a total of 25 Yemenis were killed, including 10 children, drawing criticism by international rights groups and calls for an inquiry.

Al-Jaouf added that the top tribal figure, Abdel-Elah al-Dhahab, whose brothers were accused of links to al-Qaeda and were killed in the January raid, survived the latest strikes.

On Thursday, Capt. Jeff Davis, a Pentagon spokesman, said the latest strikes were aimed at degrading the group's ability to 'coordinate external terror attacks' and to limit its use of Yemen as a 'safe space for terror plotting.'

Al-Qaeda in the Arabian Peninsula, as the Yemen affiliate is known, has long been seen as the global network's most dangerous branch, and has been implicated in a number of attempted attacks on the US homeland.

The group has recently exploited the chaos of Yemen's civil war, which pits Shiite Houthi rebels and allied army units against a Saudi-led coalition battling to restore the internationally recognized government.