A Saudi-led air strike hit a base in central Yemen killing 15 rebels on Sunday as 12 people died in overnight fighting in main southern city Aden, medical and security sources said.
The pre-dawn strike hit Camp 22 in Al-Dhahra in the south of Taez province and also wounded eight Huthi Shiite rebels or allied troops, a medic at Al-Thawra hospital said.
The base belongs to the elite Republican Guard which remained loyal to former president Ali Abdullah Saleh after he was forced from power in 2012 following a year of nationwide protests against his three-decade rule.
Saleh has allied his followers with the Huthi rebels, who overran the capital Sanaa in September, in their battle against forces loyal to fugitive President Abedrabbo Mansour Hadi.
The Saudi-led coalition said on Saturday that it had conducted 1,200 air strikes since March 26 and neutralised the air and missile capabilities of the rebels and their allies.
The air campaign, which has been accompanied by a naval blockade, was launched as the rebels closed in on Hadi`s refuge in Aden.
The president escaped to neighbouring Saudi Arabia as the rebels and their allies entered the port city sparking fierce fighting with his loyalists.
Four civilians were shot dead in the city`s Mualla and Dar Saad districts on Saturday, a medic at the Ba-Suhaib military hospital said.
A Hadi loyalist blamed rebel snipers for the deaths.
In the west of Aden, five rebels and three loyalist militiamen were killed in clashes that flared as the rebels tried to advance towards the city`s oil refinery, sources on both sides said.
Since the air campaign began, fighting has flared in 15 of Yemen`s 22 provinces.
These include Aden, Daleh, Lahj, Abyan and Shabwa in the formerly independent south, where locally recruited militia have remained loyal to Hadi.
Taez, Ibb, Baida, Hudeida, Raymah, Amran, Hajja, Saada, Jawf and Marib have seen clashes between the rebels and tribes loyal to Hadi, or with Saudi troops across the border.
Meanwhile, Al-Qaeda militants have taken advantage of the security vacuum to seize control of Mukalla, the capital of Hadramawt province in the southeast.