Five civilians were killed and eight wounded on Monday in an air raid on a rebel-held town in south Yemen, an official said, days after the United Nations agreed to investigate war crimes in the country.

Speaking to AFP on condition of anonymity, the government official said the raid targeted the Barh district in the southern province of Taez, which is largely controlled by Yemen's Saudi-backed government.

Barh, however, is held by the country's Shia Houthi rebels, who are allied with Iran.

The rebel-run Saba news agency said Saudi Arabia was behind the raid. Saudi officials did not comment on the news on Monday.

Allied with former president Ali Abdullah Saleh, the Houthis for years have been locked in a war with the government of President Abedrabbo Mansour Hadi, in turn supported by an Arab military coalition led by Saudi Arabia.

More than 8,500 people have been killed and nearly 49,000 wounded since the Saudi-led coalition joined the Yemen war in 2015.

The UN Human Rights Council last week agreed to send war crimes investigators to Yemen, overcoming strong resistance from Saudi Arabia.

The United Nations has warned more than 17 million Yemenis now face dire food shortages.

Another 2,100 people have died in a cholera epidemic which erupted in April and could infect as many as 900,000 people by the end of 2017, according to the International Committee of the Red Cross.