At least 10 suspected al-Qaeda fighters have been killed in a US drone strike in southern Yemen.
The strike on Friday happened near Radaa city, where Shia Houthi rebels are trying to seize territory held by al-Qaeda.
The US struck positions believed to be held by al-Qaeda near areas that have seen intense fighting between the the group and the Houthis.
Al Jazeera's Omar Al Saleh, reporting from Aden in southern Yemen, said the attack had concentrated on three areas believed to be al-Qaeda strongholds.
"It is not clear if the victims are in fact al-Qaeda fighters," he said. "Some sources are telling us they could be tribesmen.
"Some of the tribes have united with al-Qaeda in the area because they are angered by the Shia Houthi advance into areas of Radaa city. There is a territorial aspect to this, but also a sectarian one," Al Saleh said.
Dozens of Houthis were reportedly killed in clashes as they tried to advance on Radaa on Saturday.
Tribal sources said al-Qaeda fighters surrounded the Houthis on a mountain in the area at dawn, killing dozens and taking 12 prisoners.
The security situation in Yemen is deteriorating, and there are fears the country could slide into civil war if an agreement on forming a unity government cannot be reached.
A deadline for agreement on a unity government has already passed, increasing fears that a UN brokered peace plan signed last month by the leaders of the Houthi rebels and the Yemen government will not take effect.
"The Houthis are very much engaged in talks over forming a unity government." Al Saleh said. "According to our sources they have secured at least six posts, which reflects their increasing political power."
The Houthis, led by Abdulmalik al-Houthi, also said they would give an administerial post to Yemen's southerners, our correspondent said, seen by many as a placatory gesture to try to appease the south's continued push for independence from the country.
Source: Al Jazeera and agencies