An air raid in Yemen has killed at least 20 people mostly from the same family, the United Nations (UN) and witnesses said Wednesday, the latest in a series of suspected strikes on civilians by a Saudi-led coalition.

The attack on Tuesday afternoon hit a group of civilians in the Mawza district of the southwestern province of Taez, a statement by the UN refugee agency said.

Residents said the attack was carried out by a warplane from the Saudi-led coalition fighting rebels in support of Yemen's internationally recognised government.

At least seven women and four children were among those killed, they said.

The United Nations High Commissioner for Refugees (UNHCR) said it was “deeply shocked and saddened at reports of the deaths and injuries of a number of internally displaced persons in an aerial attack” on the area.

The statement said the civilians had fled fighting in the nearby Mokha district, on the Red Sea coast.

Coalition-backed forces loyal to Yemen President Abd Rabbu Mansour Hadi recaptured the port of Mokha in February as part of a major ongoing offensive to drive rebels from Yemen's lengthy coastline.

The UNHCR statement said more than half a million civilians, 27 per cent of Yemen's internally displaced people (IDPs), originate from the governeorate of Taez.

'Extreme dangers'

“This latest incident once again demonstrates the extreme dangers facing civilians in Yemen, particularly those attempting to flee violence, as they disproportionately bear the brunt of conflict,” the statement said.

The coalition launched a military operation against the rebels in March 2015 as insurgents closed in on Hadi in his southern refuge in Aden forcing him to flee to Riyadh.

The World Health Organisation estimates that more than 8,000 people have been killed in Yemen's conflict, most of them civilians, since the intervention.

The Saudi-led coalition has faced repeated criticism over civilian casualties in Yemen. It accuses the rebels of using civilians as human shields.

Last month, an air raid on a market in rebel-controlled Saada province, in north Yemen, killed 24 civilians.

Another suspected coalition raid in Taez province in May was reported to have killed more than 20 civilians.

The coalition has admitted responsibility for some strikes that killed civilians, including a raid on the rebel-held capital Sanaa in October 2016 that killed more than 140 people at a funeral ceremony.

The UNHCR statement said appealed for parties to the conflict to do “their utmost in the protection of civilians and the mitigation of suffering.”

“A peaceful political solution to resolve the conflict in Yemen is urgently needed to end civilian suffering,” it said.

Repeated attempts to bring about a political solution to the conflict, including a series of UN-mediated peace talks, have failed.

The Houthi rebels seized control of large parts of the country including Sanaa in late 2014 and early 2015.

Campaigners in the West have urged countries including the United States and Britain to suspend arms exports to Saudi Arabia over civilian casualties in the conflict.