British arms companies have earned more than £6bn from their trade with Saudi Arabia during the ongoing war in Yemen, new research has found.

War Child UK claimed the true revenue from dealings with the Gulf state are almost double previous estimates, despite only around £30m going to the public through corporation tax receipts.

The charity accused private manufacturers including BAE Systems and Raytheon of “profiteering from the deaths of innocent children” by selling missiles and equipment to the Saudi-led coalition.

It stands accused of committing war crimes and killing thousands of civilians with its bombing campaign against Houthi rebels.

Rocco Blume, a conflict and humanitarian advisor at War Child, said Britain is not only selling arms to Saudi forces but maintaining them as well.

The estimated revenue from ongoing support pushed the estimated revenue far above the £3.6bn figure announced by the Campaign Against the Arms Trade last week.

“We all want to see productive international trade, but this is damaging,” Mr Blume told The Independent.

“The revenue has to be seen in the context of all the other costs incurred in this trade, especially to our international reputation, particularly on human rights.”

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

Mr Blume said there was a “lack of transparency” on the extent of British firms’ involvement amid a global weakening of protections for children in conflicts including Yemen, Syria and Iraq.

He also raised concern that the UK was becoming “less fussy” about international trading partners as Brexit approaches.

BAE Systems and Raytheon were among the exhibitors at an arms fair held in London last week, which was supported by Government ministers and senior military commanders.

Liam Fox, the International Trade Secretary, defended the “ethical” trade at the Defence and Security Equipment International (DSEI) event, telling delegates that Britain’s licensing system ensured exports are lawful and the UK does not violate international law.

The following day, the Sir Michael Fallon outlined his vision for the UK to take a bigger share of the international defence market after Brexit.

Mr Fallon said the UK secured defence orders totalling £5.9bn in 2016 and is already the world’s second-largest weapons exporter.

But War Child said there was a disparity between the economic benefit to the British public versus the profit for private firms inside the arms industry, which is estimated at almost £600m.

Ministers championed the arms trade at the DSEI arms fair in London (Lizzie Dearden)

It found that an estimated tax revenue of 45 pence per head was “dwarfed” by pay and bonuses, as well as the amount spent by the Government on aid to Yemen.

A spokesperson said: “Weapons sales to Saudi Arabia generated just £13m in corporation tax in 2016, yet during 2017, the UK will spend £139m in humanitarian aid to Yemen.

“This means the Treasury is spending over four times in aid what it is getting back in tax.”

The Government has been forced to repeatedly defend the trade amid evidence of war crimes and civilian deaths in Yemen, where Saudi-led bombardment is worsening a hunger crisis and cholera epidemic.

Evidence found at the scene of massacres suggests some were carried out by British-made weapons, including Raytheon’s laser-guided Paveway IV smart bomb, which is manufactured in Fife.

In two years of civil war in Yemen, an estimated 1,300 children have been killed and 2,000 more injured, with 212 schools attacked and medical facilities destroyed and millions at risk of famine and cholera.

Yasser, 12, told War Child his mother, father and three siblings were killed in an air strike in northern Yemen.

“The first rocket fell on the hospital gate,” he said. “The sound was terrifying. I saw the bodies of people. Even my father was killed. I was afraid so I ran away to the mountains.”

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

A 10-year-old boy called Sameer told how he left for school near Sana’a before his brother and returned home to find their house destroyed, and everyone inside dead.

Saudi Arabia was blacklisted by the United Nations for committing grave violations against children last year but later removed from the list after protests from the country’s government.

MPs and humanitarian organisations have called on the Government to end arms sales to Riyadh, but it won a legal challenge mounted by the Campaign Against the Arms Trade in July.

The High Court ruled that the trade did not break the law because there was no evidence of the Saudi-led coalition deliberately targeting civilians, while it investigates alleged civilian casualties.

Lord Justice Burnett told the Court 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”.

The Government has publicly restated its support for Saudi Arabia’s role in Yemen, saying it is supporting President Abdrabbuh Mansour Hadi against Houthi rebels and forces loyal to the former president.

But Rob Williams, the CEO of War Child UK, said it was “morally repugnant that the UK government is allowing companies to make killer profits from the deaths of innocent children”.

“Thousands of children have died and millions more are at risk,” he added.

“The British Government is shamefully complicit in their suffering and justifies it with promises of economic prosperity, which this report embarrassingly discredits.”

A spokesperson for the Department for International Trade said: “The UK Government takes its defence export responsibilities very seriously and operates one of the most robust export control regimes in the world.