The government has apologised for breaching a court ruling against the sale of weapons to Saudi Arabia that could be used in the Yemen conflict.

Liz Truss, the international trade secretary, admitted the government approved two licences for military equipment which could be used in the civil war.

This is despite the government freezing new arms licences for Saudi Arabia in June after the Court of Appeal ruled that it was unlawful for the government to license weapons exports without assessing whether there was a “historic pattern of breaches of international humanitarian law” by the Saudi-led coalition.

Ms Truss wrote to the chair of the Committees on Arms Export Controls on Monday, informing them that she had apologised to the Court of Appeal for unintentionally breaching the ruling.

She said: “The government legal department has today informed the Court of Appeal of two inadvertent breaches.

“I have apologised to the court unreservedly for the error in granting these two licences.”

Ms Truss said she also told the court about two other licences that have not breached the ruling, but which are “inconsistent with the broader commitment” made by the government not to grant licences for any equipment that could be used in the Yemen conflict.

In her letter, Ms Truss said the first licence was for a £200 air cooler which would be incorporated in a light armoured vehicle to be used by the Royal Saudi Land Forces (RSLF) in Saudi Arabia.

It was approved on the basis the RSLF was not operating in Yemen, however the Foreign Office was later informed by the British Embassy in Riyadh that RSLF troops were deployed in Yemen, she said.

Since the court ruling, a licence was also granted for 260 items of various radio spares, worth about £435,450, for the RSLP Signal Corps.

Ms Truss said: “Our current understanding is that 180 items have been shipped, with a value of £261,450, leaving 80 items licensed but unshipped with a value of £174,000.”

The Campaign Against Arms Trade (CAAT) claims the UK has licensed £5.3bn worth of arms to Saudi Arabia since the conflict in Yemen began in March 2015.

Andrew Smith, of CAAT, said: “We are always being told how rigorous and robust UK arms export controls supposedly are, but this shows that nothing could be further from the truth.

“If the government cannot be trusted to follow its own rules, or an order from the Court of Appeal, then it must immediately end all arms exports to the Saudi regime and cease all support for this devastating war.”

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Barry Gardiner, the shadow international trade secretary, called for Ms Truss to resign if she “cannot control her department, obey the law and do what is morally right”.

He added: “The people of the United Kingdom do not want to be complicit in fuelling the humanitarian crisis in Yemen and the secretary of state must immediately suspend all arms sales to Saudi Arabia.

“Thousands of people have been killed in this war and it is staggering that the trade secretary thinks an apology will get her off the hook.”