At least 35 workers have been killed by a blast at a dairy factory in western Yemen, as Saudi-led air strikes continue against Houthi rebels.
There were conflicting reports about the cause of the overnight explosion in the Red Sea port city of Hudaydah.
Witnesses said "coalition aircraft hit warehouses belonging to the factory. Anti-aircraft guns then returned fire, before the factory itself caught fire."
UN alarm on casualties
The UN has expressed alarm at the rising number of civilian casualties.
On Tuesday, the high commissioner for human rights warned that Yemen seemed to be "on the verge of total collapse."
A 10-nation coalition led by Saudi Arabia has been conducting air strikes on the Houthis and allied army units loyal to former President Ali Abdullah Saleh for a week, with the stated aim of 'defending the legitimate government' of President Abdrabbuh Mansour Hadi.
Mr Hadi fled abroad last week after the Zaidi Shia rebels advanced on the southern city of Aden, where he had taken refuge after the Houthis took full control of the capital Sanaa in January and placed him under house arrest.
Overnight, coalition aircraft targeted rebel positions in Hudaydah. Witnesses said that the factory caught fire after warplanes bombed nearby warehouses and rebel anti-aircraft batteries returned fire.
"The blaze triggered explosions inside the factory that caused parts of the building to collapse with workers still inside, the witnesses said.
Factory used to store weapon
Two military officials stated that the factory had been used by the rebels to store weapons and that while the air strikes destroyed the warehouses, the factory was only partially destroyed. "That suggested it might have been hit from the ground," they added.
The health authorities in Hudaydah province said at least 35 workers were killed, many of them crushed by rubble or burned to death.
Hudaydah's governor, Hassan al-Hai, said dozens of people were also wounded, but he did not say if the factory was hit by an air strike or shelling by the rebels.
The Saudi-led coalition also bombarded Houthi positions in Aden overnight. A military official said there were "many dead and wounded."
The coalition has insisted that it is trying to avoid killing civilians.
"Collateral damage can happen... but I confirm to you that the coalition takes all care," spokesman Brigadier General Ahmed Asiri stated. But on Tuesday Amnesty International accused Saudi Arabia and its allies of "turning a blind eye to civilian deaths," and the UN Children's Fund, Unicef reported that at least 62 children had been killed and 30 hurt over the past week.
The Houthis have said their aim was to replace President Hadi's government, which they accuse of being corrupt. Their leader has refused to surrender to what he called the 'unjustified aggression' by the coalition.
Regional Shia power Iran, which has denied accusations from Saudi Arabia that it is offering the rebels military assistance, has demanded an immediate halt to the air strikes.