Israel has labeled prominent Palestinian human rights organizations as "terrorist", claiming that they secretly work for the PFLP.

It could perhaps be true that there are people in those organizations that secretly work with some PFLP activists. It might be difficult for the organizations to prevent that, or even find out about it.

But given Israel's history of distortions and lies in regard to Palestinians, and its contempt for their human rights, I don't consider it plausible. I have more confidence in B'tselem.