London (CNN) British arms sales to Saudi Arabia were unlawful because they did not properly consider whether the weapons would be used to commit "serious violations of international humanitarian law," the UK Court of Appeal ruled Thursday.

The ruling will not halt British arms sales to Saudi Arabia, which is deeply involved in the civil war in Yemen, but it does mean the British government "must reconsider the matter," the court ruled.

It is a victory for anti-arms trade campaigners concerned about the cost to civilian lives caused by British bombs and fighter jets sold to the Saudis, including the Campaign Against Arms Trade (CAAT), which brought the case and hailed the ruling.

However, CAAT added Thursday: "It shouldn't take four years of schools, hospitals, weddings, and funerals being bombed. It should not take tens of thousands of deaths and the worst humanitarian crisis in the world."

Export licenses for military goods to Saudi Arabia approved by the UK government since the bombing of Yemen began in March 2015 are worth $5.9 billion, according to data analyzed by CAAT

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