A lethal drone used by Israelis to kill over 800 Palestinians in raids against the Gaza Strip is being used as the basis for a similar machine being developed for the UK military.
The Watchkeeper drone is supposed to be used by the British military for surveillance purposes, but campaigners fear the Royal Artillery will one day put weapons on the model to make it a viable hostile option for future warzones.
It is being developed in a joint venture between defence firm Thales UK and Haifa-based defence firm Elbit, which is behind the deadly Hermes 450 model used extensively by Israel in Gaza.
The charity War On Want is now demanding a two-way arms embargo against Israel.
It also wants the European Union to cease providing funding for the security research programme which Israeli arms companies participate in.
"By supporting the arms trade with Israeli companies, the British government is sending a clear message of approval for Israel’s aggression against the Palestinian people," War On Want's senior campaigns officer Rafeef Ziadah said.
"It is high time both the UK and the EU ended their support for Israel's violations of international law."
The British government currently has 381 arms licences with Israel worth £7.8 billion, the charity said.
It called on ministers to impose a two-way arms embargo as a punishment for Israel's "violations of human rights".
One drone strike in late 2012 left 36 people dead in Gaza.
Twelve-year-old victim Mamoun Aldam said: "I held my Mamoun in my arms when he died and everything felt destroyed for me. I hope that he is the last child to be killed in Palestine."