The Dutch ban on exporting spare parts for F35 fighter jets to Israel can remain in place, the Supreme Court’s most senior legal advisor said on Friday.

Advocate general Paul Vlas said that the appeal court was “justified in concluding that there is a clear risk that Israel’s use of F-35 fighter jets could lead to serious violations of international humanitarian law in Gaza”.

“Based on various international agreements to which the Netherlands is a party, the export of military goods must be prohibited if such a clear risk exists,” the advocate general said.

Oxfam Novib, Pax Nederland, and The Rights Forum filed the civil complaint last December, arguing that shipping F-35 parts which are owned by the United States but stored in a warehouse on Woensdrecht air base, makes the Dutch complicit in war crimes in Gaza.

In January a lower court rejected the complaint, saying the situation was unclear. But the groups won on appeal in February. “It is undeniable that there is a clear risk that the exported F-35 parts are used in serious violations of international humanitarian law,” judge Bas Boele said at the time.

The UN’s highest court, the ICJ, has issued three sets of emergency measures ordering Israel to respect international law in Gaza. The ICC has opened an investigation into Palestine and issued arrest warrants for Israeli prime minister Benjamin Netanyahu, minister of defense Yoav Gallant and one Hamas leader.

The advocate general’s opinion is not binding on the court but is often followed. The Supreme Court will publish its ruling as soon as possible.