An airstrike has hit a Doctors Without Borders hospital in Yemen, with 20 people reportedly killed or wounded.

The Saudi-led coalition airstrike hit the hospital in Abs, in Yemen's northern Hajja province.

Yemeni officials told Reuters at least seven people had been killed and at least 13 had been wounded.

A Reuters witness said medics could not immediately evacuate the wounded because war planes continued to fly over the area and they feared more bombings.

The facility is run by aid group Medecins Sans Frontieres.

An MSF spokesman said: "MSF is currently assessing the situation to secure the safety of patients and staff. The number of casualties is still unknown while medical teams are assisting the wounded."

MSF said it has supported ABS hospital since July 2015 and treated 4611 patients there.

Yemen is embroiled in a deadly civil war with rival forces battling for control of the country.

A rebel group known as Houthis seized control last January, triggering a Saudi-led military intervention.

The conflict is seen as a lightning rod for regional tension between Shia-ruled Iran and the Sunni-led Saudi Arabia.