At least 20 civilians have been killed in an air strike by the Saudi-led coalition while attempting to escape fighting in Yemen, according to the UN and witnesses.

Survivors said a vehicle packed with families fleeing battles between government forces and Houthi rebels near the city of Taiz was hit on Tuesday.

Officials said many of those killed were from the same family, including women and children.

The UN Refugee Agency (UNHCR) said it was “shocked and saddened” by the deaths in the Mawzaa district, where civilians had been displaced by intensified hostilities in the nearby port of Mocha.

“Nowhere in Yemen safe for civilians,” said UNHCR spokesperson Shabia Mantoo.

“Each of Yemen's mainland governorates is affected by conflict and tens thousands have been killed and injured.

“We have been advocating incessantly for respect of international humanitarian law and protection of civilians in Yemen. More must be done.”

Michael Fallon claims Saudi Arabia is only 'defending itself' when attacking Yemen

Ms Mantoo told The Independent it was a “travesty” that civilians displaced by the conflict are being trapped in areas themselves hit by violence, with numerous sieges underway.

More than a quarter of all men, women and children forced from their homes in Yemen are from Taiz governorate, but it also hosts 15 per cent of the country’s internally displaced people.

International rights groups have accused the Saudi-led coalition of bombing civilian gatherings, markets, hospitals, and residential areas across Yemen since the beginning of its campaign in support of President Abdrabbuh Mansour Hadi in 2015.

Saudi Arabia is using British-manufactured weapons in the offensive, sparking failed legal challenge by the Campaign Against the Arms Trade in the High Court.

Judges found that the Saudi-led coalition was “not deliberately targeting civilians” and alleged massacres were under investigation, concluding that it had not been established that there was “a clear risk that the items might be used in the commission of a serious violation of international humanitarian law”.

Dr Abdullah al-Rabeeah, a former Saudi minister and now head of the country’s state aid agency, told The Independent “there is no intention whatsoever to bombard or kill civilians”.

The situation in Yemen Show all 14 1 /14 The situation in Yemen The situation in Yemen Houthi supporters trample on a US flag during a gathering mobilizing more fighters into several Yemeni battlefronts, in Sana'a, Yemen EPA The situation in Yemen People carry the coffins of men, who were killed in the recent Saudi-led airstrikes during their funeral, in the Old City of Sanaa, Yemen AP The situation in Yemen Pro-government fighters give food to Yemeni children on the road leading to the southwestern port city of Mokha. Yemeni rebels are putting up fierce resistance in a key Red Sea port city where they are encircled by pro-government force Getty Images The situation in Yemen A Yemeni stands in front of a graffiti protesting US military operations in war-affected Yemen, in Sana'a, Yemen. According to reports, US Special Forces troops allegedly disembarked from US helicopters in the Yemeni town of Yakla and attacked several houses belonging to members of the terrorist group Al-Qaeda, killing three high-ranking Al-Qaeda members and nine civilians, six women and three children. One American serviceman has been killed and three injured in the attack EPA The situation in Yemen US Special Forces troops allegedly disembarked from US helicopters in the Yemeni town of Yakla and attacked several houses belonging to members of the terrorist group Al-Qaeda, killing three high-ranking Al-Qaeda members and nine civilians, six women and three children. One American serviceman has been killed and three injured in the attack EPA The situation in Yemen A Yemeni female fighter supporting the Shiite Huthi rebels, and carrying weapons used for ceremonial purposes, takes part in an anti-Saudi rally in the capital Sanaa Getty Images The situation in Yemen Yemeni female fighters supporting the Shiite Huthi rebels, and carrying weapons used for ceremonial purposes, take part in an anti-Saudi rally in the capital Sanaa Getty Images The situation in Yemen A boy shouts slogans next to pro-Houthi fighters, who have been injured during recent fighting, during a rally held to honour those injured or maimed while fighting in Houthi ranks in Sanaa, Yemen Reuters The situation in Yemen Balls of fire and smoke rise from a Houthi-held military camp following alleged Saudi-led airstrikes, in Sana'a, Yemen EPA The situation in Yemen Yemenis search under the rubble of damaged houses following reported Saudi-led coalition air strikes on the outskirts of the Yemeni capital Sanaa Getty Images The situation in Yemen A Yemeni boy looks on as Yemenis search under the rubble of damaged houses following reported Saudi-led coalition air strikes on the outskirts of the Yemeni capital Sanaa Getty The situation in Yemen A Yemeni boy sits amidst the rubble of damaged houses following reported Saudi-led coalition air strikes on the outskirts of the Yemeni capital Sanaa AFP/Getty The situation in Yemen Marine One with US President Donald Trump flies with a decoy and support helicopters to Dover Air Force Base in Dover, Delaware, for the dignified transfer of Navy Seal Chief Petty Officer William 'Ryan' Owens who was killed in Yemen Getty Images The situation in Yemen US President Donald Trump aboard the Marine One to greet the remains of a US military commando killed during a raid on the al Qaeda militant group in southern Yemen on Sunday, at Dover Air Force Base, Delaware, US Reuters

“When there is a conflict there will be mistakes, but we account for our mistakes and apologise for them, and try to compensate those who have been hurt,” he added, claiming the autocracy was also the “number one donor” for aid and development in Yemen.

While the conflict is killing 75 people every day, according to UN figures, many more are falling victim to a cholera outbreak and severe food shortages pushing the country to the brink of famine.

Separately, UN officials said the coalition barred one of its flights to Yemen's Houthi-controlled capital, Sana’a.

The plane was going to bring aid workers and BBC reporters from Djibouti. The coalition shut down the city’s international airport a year ago.

The war has been mired in stalemate for most of the last two years, with more than 10,000 civilians killed and three million displaced.