In regards to the Palestinians/Israelis this appears to be a malicious lie. If you look into it you see weird claims like poisoning people to take their organs (this ruins the organs) and taking people from graveyards for the recently killed (you don't bury people and then come back for their shit) .
The allegations being a mix of unlikely claims and provable lies suggests there is no merit whatsoever to such claims.
It is difficult to prove non-existence. Do you have some reliable sources I can read that show this behavior? Sources who preferably don't make weird assertions or constantly spout provable lies in other respects? It doesn't count if its a reliable source that is merely reporting "unreliable source says ___"
As an example if the Washington Post reported that $KNOWN_CRANK says 'aliens are among us' the Washington Post is taking ownership of the fact that $KNOWN_CRANK said not not the veracity of the crazy claim which is left to stand or fall entirely on the credibility of $KNOWN_CRANK.