Britain's High Court ruled on Monday that UK arms exports to Saudi Arabia are not unlawful, after campaigners argued the weapons were used to violate international humanitarian law in bombing Yemen.

"We have concluded that the material decisions of the secretary of state were lawful. We therefore dismiss the claim," Lord Justice Burnett said at the court in London.

He added it was not established that there was "a clear risk that the items might be used in the commission of a serious violation of international humanitarian law".

Half the evidence presented in the case was heard in secret after the government argued it could not be heard in public for national security reasons.

Campaign Against Arms Trade, the non-profit organisation behind the legal challenge, said that they are pursuing an appeal.

Amnesty International described the ruling as a "deadly blow for Yemenis," while Save the Children said the evidence showing the Saudi-led coalition had repeatedly violated international humanitarian law in Yemen "is overwhelming".

"It has been documented by UN reports, by aid groups on the ground and by credible human rights organisations," it said in a statement.

For the past two years, Yemen has been plunged into a civil war between Shiite Huthi rebels and government forces backed by a Saudi-led Arab military coalition.

The World Health Organization estimates that more than 8,000 people have been killed in the conflict -- most of them civilians.

The UN Office for the Coordination of Humanitarian Affairs has described Yemen as the "largest humanitarian crisis in the world".

Mark Goldring, Oxfam's chief executive said that despite the ruling in its favour, "there is a clear moral case for the government to suspend its sales".

"It must now put its diplomatic weight behind a search for peace," he added in a statement.

Saudi Arabia is Britain's largest trading partner in the Middle East, with exports of more than £6.5 billion ($8.4 billion, 7.4 billion euros) in British goods and services to the country in 2015.

source: AFP