A air strike by the Saudi-led coalition against a radio station in Yemen's Houthi-held port city of Hodeidah killed four people on Sunday, residents and medical sources said.

The bombing on a crowded market in rebel-held northern Yemen killed a total of 51 people, according to the Red Cross.

An air attack by the Saudi-led coalition in Yemen last month that killed dozens of people, including children travelling on a bus, lacked military justification and requires a review of the rules of engagement, a coalition body said on Saturday.

Saudi Arabia is leading a Western-backed alliance of Arab states trying to restore the internationally recognised government of Yemeni President Abd-Rabbu Mansour Hadi.

Fifty-six children were also among the 79 people wounded in the Thursday strike on Saada province, a rebel stronghold that borders Saudi Arabia.

The United Nations has called for a "credible" investigation into an airstrike that killed at least 29 children in Yemen, but experts and aid groups doubt that a probe announced by the Saudi-led coalition bombing the country will yield results.

At least 29 children were among those killed in the air raid on Thursday on a bus in a crowded market in Dahyan, Saada province, according to the International Committee of the Red Cross.

A Yemeni health official and the International Committee of the Red Cross said than an air strike had hit the bus carrying children as it drove through a market in northern Saada province.

The coalition said it had carried out what it called "legitimate military action" in the area targeting Houthi rebels.

Yemeni government forces backed by a Saudi-led coalition have been conducting an offensive to capture Hodeida from Iran-backed Houthi rebels.

A Saudi-led coalition launched heavy air strikes on Yemen's main port city of Hodeidah on Friday, in an apparent resumption of military operations on the city after the Iranian-aligned Houthi movement attacked two Saudi oil tankers, residents said.

Forces backed by a Saudi-led coalition have killed eight members of Lebanon's Hezbollah group in Yemen in battles with the Iran-aligned Houthis, the coalition said on Monday.