The missile hit the clinic in the Razeh district of Saada province in northern Yemen, communications officer Malak Shaher said on Sunday.

Doctors Without Borders (MSF) also announced the attack on its Twitter account.

Shaher said it was not possible to say whether the clinic was hit in an airstrike by the Saudi-led coalition that is carrying out attacks on Iran-backed Shiite Houthi rebels in Yemen, or by a rocket fired from the ground.

Last month, MSF accused the coalition of bombing another of its health facilities in Taez in October. The building was wrecked and two MSF staff members lightly wounded in that attack.

The coalition said at the time that it would investigate the claim.

After Sunday's attack, MSF called on all warring parties in Yemen to respect medical facilities.

Bloody conflict

More than 5,800 people have been killed in Yemen since March, about half of them civilians, according to United Nations figures.

The conflict in the country pits forces loyal to internationally recognized President Abd Rabu Mansour Hadi against the Houthi rebels and fighters loyal to former President Ali Abdullah Saleh.

The fighting has its roots in a Houthi insurgency that has been waged with varying intensity since 2004.

In 2015, Saudi Arabia formed a coalition of nine Arab states to help the internationally recognized Yemeni government by launching airstrikes on its enemies including the Houthi rebels, whom Riyadh sees as proxies for its regional rival, Iran. The campaign has been widely criticized for worsening the humanitarian situation in Yemen.

tj/gsw (Reuters, AFP)