A Yemeni rebel attack near the country's northwest border with Saudi Arabia has killed 14 Sudanese soldiers, Yemeni military sources said Friday.

Sudan is part of a Saudi-led military coalition that has been supporting Yemen's internationally recognised government since 2015 in its battle against rebels.

The soldiers were killed when the militants attacked coalition sites in Haradh, in Hajja province on Thursday, the sources told AFP.

Sudan, ranked by the United Nations as among the poorest in the world, has sent thousands of soldiers to fight in Yemen.

In late 2019, Sudan's transitional government said the country had reduced its troop strength in Yemen from 15,000 to 5,000.

The Yemen conflict, which began in 2014 after rebels seized the capital Sanaa, has sparked what the United Nations calls the world's worst humanitarian crisis.

Millions of people have been displaced and more than 80 percent of the population of around 30 million requires humanitarian assistance.

A UN Development Programme report last month said the war will have claimed 377,000 lives by the end of the year through both direct and indirect impacts.

Nearly 60 percent of deaths will have been caused by consequences such as lack of safe water, hunger and disease, it said, suggesting that fighting will have directly killed over 150,000 people.