Campaigners aiming to stop Britain selling arms to Saudi Arabia to prevent their use in Yemen’s war can appeal after losing their case last year, a British court ruled on Friday.

Last July, the Campaign Against Arms Trade (CAAT) sought a High Court order to block export licenses for British-made fighter jets, bombs and other munitions it said were being used by a Saudi-led military coalition that intervened in Yemen’s conflict in 2015, leading to hundreds of civilian deaths.

The High Court ruled that the granting of licenses for arms exports from Britain to Saudi Arabia was not unlawful. CAAT took its case to the Court of Appeal, which decided on Friday to hear the case in the coming months.

Andrew Smith of CAAT said his group believed the sales were immoral. “The Saudi-led bombardment of Yemen has killed thousands of people and created one of the worst humanitarian disasters in the world,” he said after Friday’s judgment.

“Despite this, the Saudi regime has been armed and supported every step of the way by successive UK governments. We believe that these arms sales are immoral, and are confident that the Court of Appeal will agree that they are unlawful.”

Over 10,000 people have died in Yemen since Saudi Arabia’s Western-backed alliance launched its campaign to restore the internationally recognized Yemeni government. It has carried out thousands of air strikes against the Iran-allied Houthi movement that controls much of north Yemen including the capital Sanaa.

Errant air strikes have killed hundreds of civilians at hospitals, schools and markets. Two weeks ago, coalition warplanes killed at least 20 people attending a wedding in a village in northwestern Yemen.

The coalition denies targeting civilians in its campaign.

The United Nations says food shortages caused by the warring parties blocking supplies has created the world’s worst humanitarian crisis. The conflict has displaced more than 2 million people and triggered a cholera epidemic that has infected about 1 million people.

British exports to Saudi Arabia have provided billions of pounds of revenue for the British arms trade, but opposition has grown as the conflict and humanitarian crisis in Yemen worsened.

Prime Minister Theresa May has defended British arms exports to Saudi Arabia, saying all such sales are strictly regulated, that Saudi involvement in the Yemen conflict is backed by the U.N. Security Council and her government supports it.

The issue has provoked heated debate in parliament, with the main opposition Labour party saying arms export licenses should be suspended and Britain must be held partly responsible for civilian casualties in Yemen.

“It cannot be right that the government is colluding in what the United Nations says is evidence of war crimes,” Labour leader Jeremy Corbyn told parliament in March.

Britain’s Department for International Trade said it would defend last July’s High Court decision.

“We remain confident that the UK operates one of the most robust export control regimes in the world and will continue to defend the decisions being challenged,” a spokesman said.

“We keep our defense exports under careful review to ensure they meet the rigorous standards of the Consolidated EU and National Arms Export Licensing Criteria.”