A pair of judges at the court dismissed the case brought by the Campaign Against Arms Trade (CAAT), after hearing arguments earlier this year.

The UK-based NGO accuses the government of contributing to breaches of international law and the world's largest humanitarian disaster in Yemen, where conflict has claimed tens of thousands of lives in recent years.

But the judges sided with the British government, concluding there had been "continuing rationality" in a risk assessment performed by officials before restarting arms sales to Saudi Arabia in 2020.

Riyadh has intervened militarily in Yemen since 2015, leading a regional coalition supporting pro-government forces opposed to the Iran-backed Houthi rebels.

The NGO launched the legal challenge after Britain announced the sales resumption, with ministers insisting there was no clear risk that weapons would be used in a serious violation of international humanitarian law.

The government has licensed sales to Riyadh of weaponry including combat aircraft, guided bombs and missiles, with a published value since 2015 of pound7.9 billion ($9.8 billion), according to CAAT.

Emily Apple, a spokesperson for the NGO, said it was "obviously disappointed with the verdict".

"The court's ruling, much of which was based on closed evidence that we were not allowed to hear, exposes the low threshold the government has to reach in order to sell weapons to regimes committing human rights violations," she added.