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.
Arab coalition troops stormed the airport in Yemen's main port Hodeidah on Tuesday and captured large areas of the compound in battles with Iran-aligned Houthis, a Yemeni military source, the UAE news agency and local residents said.
Yemen's Iran-aligned Houthi movement fought on Saturday to keep a Saudi-led coalition from taking full control of the airport in the port city of Hodeidah, in an offensive the UN says could trigger a famine imperilling millions of lives.
A Yemeni rebel attack killed 12 soldiers south of the battleground Red Sea port city of Hodeida on Friday, military and medical sources said.