Recently Israel designated several human rights NGOs as terrorist organizations. The six organizations are alleged to have links to the PFLP:

The Israeli defence ministry said they were linked to the Popular Front for the Liberation of Palestine (PFLP), a secular political movement with an armed wing that in the past carried out attacks against Israel.

These organizations receive funding from various international sources:

The groups, well known for their human rights work, have received funding from EU member states, the United Nations and other donors.

This designation is viewed as arbitrary by other human rights groups, for example B'Tselem:

The Israeli human rights group B’Tselem called the government’s declaration “an act characteristic of totalitarian regimes, with the clear purpose of shutting down these organisations”.

It also seems to be viewed as arbitrary by some EU states, for example Ireland:

Minister for Foreign Affairs Simon Coveney has expressed concern at the designation by Israel of six NGOs operating in the occupied Palestinian territories as terrorist entities. [..]

He said no detailed evidence had been provided by Israel.

In a statement Minister Coveney said previous allegations against civil society organisations in the territory have not been substantiated.

Apparently Israel provided no evidence that these NGOs are linked to terrorist activities. So on which basis (legal or judiciary process) was this designation made?

Edit August 2022: a recent article in The Guardian says that "Earlier this year, Israel passed intelligence about the designation to the US, but a CIA intelligence assessment of the material did not find any evidence to support the claim, according to two sources familiar with the study."