An airstrike by the Saudi-led coalition fighting in Yemen killed 19 civilians on Wednesday, including two children, according to medical workers.

The strike hit a busy vegetable market in the town of Bayt el-Faqih, south of the port city of Hodeida, which coalition forces have been battling to capture from Houthi rebels since June.

Abdullah Shahawi, the director of the hospital that received casualties, told the Associated Press that all the victims were civilians.

News of the strike came as a number of UK rights groups announced a new legal challenge over the British government’s arms sales to Saudi Arabia.

The Saudi-led coalition intervened in Yemen three years ago after Houthi rebels took over much of the country and forced out the internationally recognised government of President Abdu-Rabbu Mansour Hadi.

During that time at least 6,660 civilians have been killed, according to the United Nations, most of whom were victims of coalition airstrikes. The Houthis have also targeted civilians throughout the conflict, the UN says.

Coalition jets, backed by US logistical support and using weapons made in the US and the UK, have repeatedly hit targets where no militants were present.

In August, a strike by a coalition warplane destroyed a school bus, killing 40 boys under the age of 11. A subsequent investigation by CNN found the bomb was made by US weapons manufacturer Lockheed Martin. In 2016, a similar bomb was used in a coalition strike that killed 155 people at a funeral hall in Sanaa. The coalition blamed “incorrect information” for the attack.

The coalition has admitted to causing civilian casualties in the past, but attributes the deaths to “unintentional mistakes”, and says it is committed to upholding international law.

Aid workers say the air campaign has exacerbated the world’s worst man-made humanitarian disaster, and warned that Yemen is facing potentially its worst famine in 100 years if the conflict continues.

The children wounded in Yemen's war Show all 15 1 /15 The children wounded in Yemen's war The children wounded in Yemen's war Save the Children Child Protection staff pictured alongside Ahmed and his family to ensure ongoing physical and mental support for Ahmed at home through regular follow up visits. August 15, 2018 Ali Ashwal / Save the Children The children wounded in Yemen's war Ahmed, a 15 year-old, is lying on his bed after his leg and arm were injured during an airstrike in a market in Hudaydah. His leg is protected with Gypsum after several successful surgeries. Ali Ashwal / Save the Children The children wounded in Yemen's war Save the Children Child Protection staff pictured alongside Ahmed and his family to ensure ongoing physical and mental support for Ahmed at home through regular follow up visits. August 15, 2018 Ali Ashwal / Save the Children The children wounded in Yemen's war Save the Children Child Protection staff pictured alongside Ahmed and his family to ensure ongoing physical and mental support for Ahmed at home through regular follow up visits. August 15, 2018 Ali Ashwal / Save the Children The children wounded in Yemen's war Save the Children Child Protection staff pictured alongside Ahmed and his family to ensure ongoing physical and mental support for Ahmed at home through regular follow up visits. August 15, 2018 Ali Ashwal / Save the Children The children wounded in Yemen's war Ahmed, a 15 year-old, is lying on his bed after his leg and arm were injured during an airstrike in a market in Hudaydah. His leg is protected with Gypsum after several successful surgeries. August 15, 2018 Ali Ashwal / Save the Children The children wounded in Yemen's war Save the Children Child Protection staff pictured alongside Ahmed and his family to ensure ongoing physical and mental support for Ahmed at home through regular follow up visits. August 15, 2018 Ali Ashwal / Save the Children The children wounded in Yemen's war Ahmed, a 15 year-old, is lying on his bed after his leg and arm were injured during an airstrike in a market in Hudaydah. His leg is protected with Gypsum after several successful surgeries. August 15, 2018 Ali Ashwal / Save the Children The children wounded in Yemen's war Ahmed, a 15 year-old, is lying on his bed after his leg and arm were injured during an airstrike in a market in Hudaydah. His leg is protected with Gypsum after several successful surgeries. Ali Ashwal / Save the Children The children wounded in Yemen's war Iman* is six years old and lives in Altuhaitah district, Western Hodeidah, with her parents and six siblings. Her father is a daily labourer and earns around 500 – 1000 Yemeni Riyals (1 – 2 USD) each day. On 26th June, Iman was playing in her backyard when an airstrike hit her neighbour’s house. Shrapnel from the attack reached Iman’s home and she severely injured her neck, hand, and leg. Iman’s three-month-old brother also sustained minor injuries from the shrapnel. June 07 2018 Ali Ashwal / Save the Children The children wounded in Yemen's war Iman* is six years old and lives in Altuhaitah district, Western Hodeidah, with her parents and six siblings. Her father is a daily labourer and earns around 500 – 1000 Yemeni Riyals (1 – 2 USD) each day. On 26th June, Iman was playing in her backyard when an airstrike hit her neighbour’s house. Shrapnel from the attack reached Iman’s home and she severely injured her neck, hand, and leg. Iman’s three-month-old brother also sustained minor injuries from the shrapnel. June 07 2018 Ali Ashwal / Save the Children The children wounded in Yemen's war Iman* is six years old and lives in Altuhaitah district, Western Hodeidah, with her parents and six siblings. Her father is a daily labourer and earns around 500 – 1000 Yemeni Riyals (1 – 2 USD) each day. On 26th June, Iman was playing in her backyard when an airstrike hit her neighbour’s house. Shrapnel from the attack reached Iman’s home and she severely injured her neck, hand, and leg. Iman’s three-month-old brother also sustained minor injuries from the shrapnel. June 07 2018 Ali Ashwal / Save the Children The children wounded in Yemen's war Iman* is six years old and lives in Altuhaitah district, Western Hodeidah, with her parents and six siblings. Her father is a daily labourer and earns around 500 – 1000 Yemeni Riyals (1 – 2 USD) each day. On 26th June, Iman was playing in her backyard when an airstrike hit her neighbour’s house. Shrapnel from the attack reached Iman’s home and she severely injured her neck, hand, and leg. Iman’s three-month-old brother also sustained minor injuries from the shrapnel. June 07 2018 Ali Ashwal / Save the Children The children wounded in Yemen's war A boy injured by in the attack on a school bus in Saada, August 9th. Dozens of children aged between 6 and 14 have been killed with many more injured, after the school bus they were travelling in was hit by an airstrike in the town of Dhahyan in Saada governorate in northern Yemen. August 09, 2018 Save the Children The children wounded in Yemen's war A boy injured by in the attack on a school bus in Saada, August 9th. Dozens of children aged between 6 and 14 have been killed with many more injured, after the school bus they were travelling in was hit by an airstrike in the town of Dhahyan in Saada governorate in northern Yemen. August 09, 2018 Save the Children

The ongoing battle for the port city of Hodeida has significantly worsened the country’s food crisis. The port is a vital gateway for vital food supplies and relief for millions living in the Houthi-controlled north.

The UN’s humanitarian coordinator, Mark Lowcock, said this week that half of Yemen’s population – some 14 million people – are now facing “pre-famine conditions”.

“The toll is unbearably high. The immune systems of millions of people on survival support for years on end are now are literally collapsing, making them – especially children and the elderly – more likely to succumb to malnutrition, cholera and other diseases,” he said.

Western backers of the Saudi-led campaign have come under increasing pressure to end arms sales to the country in recent weeks amid a growing scandal over the killing of journalist Jamal Khashoggi at the Saudi consulate in Istanbul.

Saudi Arabia’s powerful Crown Prince Mohammed bin Salman – who has been the driving force behind his country’s intervention in Yemen – has faced international condemnation after it was revealed that members of his security detail were among the suspects in the killing.

Malnutrition centre in Mukalla, Yemen provides care for children suffering hunger and famine

Both the US and UK – the two top suppliers of weapons to Saudi Arabia – have cast doubt on the official version of events and said they plan to revoke the visas of the suspects in the killing, but they have also been reluctant to consider stopping arms sales.

On Thursday, Amnesty International, Human Rights Watch and Rights Watch UK said they would be launching fresh legal challenge over the UK’s arms sales to Saudi Arabia. UK military sales to Saudi Arabia reached £1.129bn in 2017, according to Department for International Trade figures.

The case is seeking to test the legality of the government’s decision to issue licences for arms exports to Saudi Arabia despite the risk of the weapons being misused in the conflict in Yemen.

“We strongly believe the UK’s sale of arms to Saudi Arabia is in clear breach of both the UK’s own law and international law,” said Rachel Logan, Amnesty International UK’s legal programme director.