Jeremy Corbyn has taken Theresa May to task over Britain’s close ties with her “war ally” Mohammed bin Salman, after she met the Saudi crown prince at the G20 summit in Japan.

Ms May says that she used her 20-minute meeting with the prince to urge him to work with the United Nations to find a solution to the long-running conflict in Yemen.

And she also called for an “open and transparent” legal process in relation to the murder of the journalist Jamal Khashoggi.

But Mr Corbyn said the PM was not going far enough in signalling the UK’s disapproval of the actions of Saudi Arabia’s de facto ruler.

“She should confirm the UK government will immediately stop selling arms to his regime and hold him to account over the horrific murder of the journalist Jamal Khashoggi,” said the Labour leader.

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 UK has pumped £4.6bn worth of military equipment into the conflict in the Yemen. Almost a quarter of a million people will have been killed by the end of this year – more than half of them under five years old.

“The Court of Appeal has found the UK government ‘made no attempt’ to conclude whether the Saudi-led coalition had committed violations of international humanitarian law in the Yemen.

“Where the UN sees ‘humanity’s biggest preventable disaster’, this Conservative government sees an arms sales opportunity.

“It is simply not good enough for Theresa May and her government to take the Saudis at their word.

“The evidence that war crimes have been committed in the Yemen, the indiscriminate attacks on civilians, the horror of mass killing and starvation, and the brutal murder of opponents at home and abroad, should mean Saudi Arabia should be held to account, not embraced as military allies.”

The crown prince has become the focus of international condemnation since taking the helm in Riyadh in 2017, due to his bombing of neighbouring Yemen and alleged links to the Khashoggi killing.

Four years of the Saudi-led bombing campaign designed to oust the Houthi rebels who hold much of Yemen have led to more than 8,000 civilian deaths and 9,500 injuries, according to the independent monitoring group Yemen Data Project. And tens of thousands more have died as a result of the fighting and disruption to food and medical supplies.

A United Nations-led peace process was threatened by allegations from the Saudi-backed official Yemeni government that the UN special envoy Martin Griffiths was siding with the rebels.

The UK government is appealing against a court ruling that arms sales to the kingdom were unlawful because of the likelihood that weapons would be used in breaches of international humanitarian law in Yemen.

Meanwhile, a trial of 11 individuals at the Riyadh Criminal Court in relation to the Khashoggi murder has been taking place behind closed doors and the defendants – five of them facing the death penalty – have not been named.

A UN report found there was “credible evidence” that the prince and senior officials were individually liable for Khashoggi’s death at the Saudi consulate in Istanbul last October.

But Riyadh insists it was the result of a “rogue operation” by agents who were intended to return him to Saudi Arabia.

G20: Theresa May touches on the murder of Jamal Khashoggi

Speaking after the meeting in Osaka, a senior British official said: “The prime minister reiterated the need to keep working on finding a solution to the current conflict in Yemen, which is causing significant humanitarian suffering, and the importance of continuing to make progress through the UN peace process.

“On accountability for the murder of Jamal Khashoggi, the prime minister said the legal process needed to be open and transparent.”

Speaking ahead of the meeting, Ms May defended her decision to sit down with world leaders like the prince and the Turkish president Recep Tayyip Erdogan, who has faced criticism for his heavy-handed response to the 2016 attempted coup in his country.

“These are all individuals sitting around the G20 table,” she said. “The G20 is about that international cooperation.