Aden, Yemen: Saudi-led coalition air strikes on rebel-held security buildings in Yemen's west, including a detention centre, killed 60 people, an official said Sunday, updating the toll from 38 dead.

"Sixty people in total were killed and dozens were wounded," said a health official from the coastal province of Hodeidah where the two raids took place on Saturday.

Most of the victims were anti-rebel detainees who were being held in two cells at the detention centre, said the source who requested anonymity.

More than 100 inmates were being held in both cells, he added.

A military source close to the insurgents said Saturday there were more than 40 inmates at the facility and most of them were held because of their opposition to the Iran-backed Huthi rebels who have held Hodeidah since late 2014.

Earlier, the same health official had put at 38 the number of inmates and insurgents killed in the air raids on the buildings in Zaidia, north of Hodeidah.

It remains unclear why the coalition would hit a detention centre holding anti-rebel inmates.

Elsewhere on Saturday, strikes on residential buildings killed 17 people and wounded seven in the battleground town of Salo, southeast of Yemen's third city Taez, said rebel-controlled media.

The sabanews.net website said four raids had completely destroyed three residential buildings.

A local official loyal to Yemen's internationally recognised government said its air strikes had hit three adjacent homes by mistake.

"All those in the houses were killed," he told AFP, adding a child and seven women were among the dead.

But the coalition has so far not commented on both attacks. 

Forces loyal to President Abedrabbo Mansour Hadi's government have been locked in deadly battles with Iran-backed Shiite Huthi rebels who overran the capital Sanaa in 2014.

The rebels are allied with troops who have remained loyal to former president Ali Abdullah Saleh.

The conflict escalated in March last year when Saudi Arabia launched a military campaign to push back the rebels.

It has killed nearly 7,000 people, mostly civilians, according to the United Nations which had been struggling to convince the warring parties to implement a ceasefire and revive a stalled political process.