An air strike by a Saudi-led coalition killed 36 civilians working at a bottling plant in the northern Yemeni province of Hajjah, residents said.

The alliance intervened in Yemen's war in March and has waged an air campaign that has rolled back some of the territorial gains of Iranian-allied Houthi forces with the goal of restoring exiled President Abd-Rabbu Mansour Hadi.

Human rights group Amnesty International said in a report this month that the campaign had left a "bloody trail of civilian death" which could amount to war crimes.

Air raids killed 65 people in the front-line city of Taiz last Friday, most of them civilians, and the bombing of a milk factory in Western Yemen in July killed 65 people including ten children.

Members of Yemen's exiled government and Saudi officials have said they are cautious to avoid civilian casualties and cite reports by human rights groups that accuse the Houthis of shelling and blockading civilian areas.

More than 4,300 people have been killed in five months of war in Yemen while disease and suffering in the already impoverished country have spread.

Militias and army units loyal to Mr Hadi have made significant gains toward the Houthi-controlled capital Sanaa in the last two months, but the group remains ensconced in Yemen's north and casualties continue to mount in nationwide combat every day.