The United Kingdom's Court of Appeal on Thursday declared British arms sales to Saudi Arabia for use in its war against Yemen "unlawful".
Thursday's decision follows a challenge by the Campaign Against Arms Trade (CAAT) that accused the UK government of licensing arms sales despite a clear risk that its use could breach the international humtarian law, Al Jazeera reported.
CAAT is a UK-based orgsation working to end the international arms trade.
Although the decision will not halt the Saudi-led war in Yemen - in which an estimated 100,000 people have died since 2016 - but it would add enormous support to international efforts to end the conflict.
Meanwhile, campaigners have hailed the ruling as "historic".
"This ruling is huge," said Sam Perlo-Freeman, a research coordinator at CAAT.
"We can see that arms sales for use in Yemen are now being challenged internationally - in the US and Europe - but this from a court in one of Saudi Arabia's top two arms suppliers takes that to a whole new level.
"It is historic in terms of the government's approach to export licences being found to be illegal and adds huge momentum to the campaign both in this country and internationally for a halt to arms sales to Saudi Arabia and the Saudi-led coalition," he added.
Since the Saudi-led coalition began its military intervention in Yemen in 2015, the UK has licensed at least 4.6 billion pounds (UD six billion) worth of arms to the Saudi forces. Weapons and military support from Britain to Saudi Arabia accounts for nearly 43 per cent of London's arms exports.
On March 6, a poll of over 2000 adults, carried out by the CAAT revealed that only six per cent of people in the country support arms sales to Saudi Arabia.
The humtarian crisis caused by the war in Yemen has been described as the world's worst and has put nearly 10 million people at risk of starvation.
( With inputs from ANI )