Doctors Without Borders is withdrawing from northern Yemen due to what it calls "indiscriminate bombings and unreliable reassurances" from the Saudi-led coalition that's fighting Shiite rebels in the country.

The international aid group said in a statement on Thursday that an attack this week on a hospital it supported in the area had killed 19 people and wounded 24.

This raises the death toll from Monday's attack on Abs Hospital, in Yemen's Hajjah governorate, after some of the wounded had died. Earlier, 11 were reported killed.

The group, known by its French acronym MSF, says the attack was "the fourth and deadliest on any MSF-supported facility during this war" in Yemen.

MSF also says that airstrikes in the north, a stronghold for the rebels known as Houthis, have intensified.