The case concerns US-owned F-35 parts stored at a warehouse in the Netherlands and then shipped to several partners, including Israel, via existing export agreements.

Oxfam Novib, one of the groups filing suit, said the export "made the Netherlands complicit in violations of the laws of war and the collective punishment of the civilian population of Gaza".

"By supplying weapons parts, the Netherlands runs the risk of becoming complicit in violations of international humanitarian law," said Dagmar Oudshoorn, director of Amnesty International.

"It is almost unbelievable that these bombs are dropped thanks to Dutch military support. This has to stop," added Michiel Servaes, director of Oxfam Novib.

Dutch authorities said last month it was not clear whether it even had the power to intervene in the deliveries, part of a US-run operation that supplies parts to all F-35 partners.

"Based on current information on the deployment of Israeli F-35, it cannot be established that the F-35 is involved in serious violations of humanitarian law of war," the government said in a letter to parliament.

But Liesbeth Zegveld, human rights lawyer for the plaintiffs told reporters: "It is clear that these planes are used above Gaza to conduct aerial bombardments and assist ground troops in Gaza as we speak."

A verdict in the case is expected in roughly two weeks.