The United Nations has blacklisted the Saudi-Arabia led coalition for killing and maiming thousands of children in Yemen.

Ban Ki-moon, the Secretary-General, said intensive bombardment had taken a “devastating toll” on the civilian population as a civil war continues to rage between the Yemeni government, Houthi rebels, al-Qaeda and Isis.

Saudi Arabia launched its intervention in support of President Abdrabbuh Mansour Hadi against the Iran-backed Houthis and their allies, who control the capital Sana’a and swathes of territory, in March last year.

UN: Six children are killed in Yemen every day

It has since gained support from Egypt, Morocco, Jordan, the United Arab Emirates, Sudan, Kuwait, Qatar and Bahrain for the air campaign.

In his annual report on children in armed conflict, Mr Ban said the UN had recorded a six-fold increase in the number of children killed and maimed in 2015 compared to the previous year.

Out of almost 2,000 child casualties and fatalities in 2014, 60 per cent - 510 deaths and 667 injuries – were attributed to the Saudi-led coalition, a fifth to Houthis and others to ground fighting and extremist attacks.

“Grave violations against children increased dramatically as a result of the escalating conflict,” Mr Ban said.

“In Yemen, owing to the very large number of violations attributed to the two parties, the Houthis/Ansar Allah and the Saudi Arabia-led coalition are listed for killing and maiming and attacks on schools and hospitals.”

MPs have raised urgent concerns about continuing British arms sales to Saudi Arabia during the conflict, while the Ministry of Defence is urgently investigating evidence of the coalition's use of British-made cluster bombs.

Amnesty International activists protesting against UK arms sales to Saudi Arabia, outside Parliament earlier this year (Getty)

The British Government says it supports the coalition’s military intervention to “deter aggression by the Houthis…allow for the return of the legitimate Yemeni Government” but would raise concerns over violations of international law with Saudi Arabia.

The UN recorded an increase in the recruitment of child soldiers, mostly by Houthis, more than 100 attacks on schools and hospitals, with 48 per cent attributed to the Saudi-led coalition, and the denial of humanitarian assistance as hundreds of thousands of children remain at risk of starvation.

The Houthis, Hadi forces and pro-government militia have been on the UN blacklist for several years and are considered "persistent perpetrators", as is al-Qaeda in the Arabian Peninsula, but the Saudi Arabia-led coalition was included for the first time.

Leila Zerrougui, the UN Special Representative for children and armed conflict, said air campaigns were worsening some wars.

“In several situations of conflict, aerial operations contributed to creating complex environments in which large numbers of children were killed and maimed,” she said.

“State-allied armed groups and militia have also increasingly been used to fight in support of Government forces, in some cases recruiting and using children.”

Fighters loyal to Yemen's President Hadi in Aden in 2016 (Getty Images)

The UN list includes groups that “engage in the recruitment and use of children, sexual violence against children, the killing and maiming of children, attacks on schools and/or hospitals and attacks or threats of attacks against protected personnel, and the abduction of children.”

Along with warring parties in Yemen, the UN inserted new listings for armed groups in Afghanistan, Democratic Republic of Congo, Central African Republic, Iraq, Mali, Burma, Somalia, South Sudan, Sudan, Syria, Colombia, Nigeria and the Philippines.

Government forces in Afghanistan, Democratic Republic of Congo, Somalia, Myanmar, South Sudan, Sudan, and Syria were also named on the blacklist.

“Situations of concern” were also recorded in India, Israel and the Palestinian Territories, Lebanon, Libya, Pakistan and Thailand.

A sports hall destroyed by Saudi-led air strikes in Sanaa (Getty)

Mr Ban urged the UN’s 193 member states to ensure engagement in hostilities and responses to threats to peace and security comply with international law, protecting civilians and children.

“It is unacceptable that the failure to do so has resulted in numerous violations of children's rights,” he said.

Kirsty McNeill, Director of Advocacy and Campaigns at Save the Children, said it was the first time an international military coalition had been put on the “list of shame”.

“The UK government must re-evaluate its diplomatic and military support to the Saudi Arabia led-coalition,” she added.

“The UK must now urgently suspend arms exports to Saudi Arabia while they risk being used in Yemen in violation of international law and throw its weight behind calls by the UNHCR, the Commons International Development Committee and Save the Children to back an international, impartial investigation into alleged violations by all sides.”

Foreign Secretary Phillip Hammond in Riyadh last October (Getty Images)

The damning report followed the Foreign Secretary’s trip to Saudi Arabia on Sunday, where he had promised to put Yemen “high on the agenda”.

Speaking ahead of the visit, Mr Hammond said Britain co-operated with Gulf states on “shared threats”, adding: “Allowing the (Yemen) state to collapse is simply not an option. Britain is continuing to work together with all parties to support a comprehensive political solution to the conflict.”

The Foreign Office has issued no information on the results of his trip but in an interview with Sky News Arabia, Mr Hammond said he had met the UN Special Envoy for Yemen to discuss the peace process.

More than a month of talks between enemy factions in Kuwait have repeatedly faltered amid continued fighting and bombardment.

A spokesperson for the Foreign Office said: “The UK supports the Saudi Arabian-led coalition’s military intervention, which came at the request of the legitimate President Hadi, to deter aggression by the Houthis and forces loyal to the former president Saleh, and allow for the return of the legitimate Yemeni Government.