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.
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.
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.