A Saudi-led coalition air strike "mistakenly" hit a position held by pro-government forces in southern Yemen Saturday, causing casualties, officials, medics and witnesses said.

At least 30 were killed and 40 others were wounded in the strike on Waziya, an area between Taez and Lahj provinces where rival forces have been fighting since late September, the medics and witnesses said.

But Abedrabbo al-Mehwali, commander of forces in the area, told AFP only "eight fighters were killed and 25 wounded."

The Arab coalition is backing loyalist forces against Iran-backed rebels in Yemen with air strikes, weapons and ground forces.

Pro-government forces retook Lahj as part of a southern offensive in mid-July that recaptured four other provinces.

But fighting has raged for months in the southwestern province of Taez, held by the rebels since last year and seen as a gateway to the capital, which they also control.

Residents told AFP the rebels have sent reinforcements to Waziya in a bid to re-enter Lahj and once more control the strategic Al-Anad airbase.

Meanwhile, three pro-government fighters were killed Saturday in rebel rocket shelling in Marib province east of Sanaa, military sources said.

Clashes are ongoing between rebels and loyal forces in Marib.

And a security official said a civilian was killed and another wounded when their vehicle hit a rebel landmine in Marib.

Around 4,500 civilians have been killed in the conflict since March.