Three former supreme court justices, including the court’s former president Lady Hale, are among more than 600 lawyers, academics and retired senior judges warning that the UK government is breaching international law by continuing to arm Israel.

The 17-page letter, which also amounts to a legal opinion, was sent on Wednesday evening and says: “While we welcome the increasingly robust calls by your government for a cessation of fighting and the unobstructed entry to Gaza of humanitarian assistance, simultaneously to continue (to take two striking examples) the sale of weapons and weapons systems to Israel and to maintain threats of suspending UK aid to Unwra falls significantly short of your government’s obligations under international law.”

The UK government has refused to publish its own legal advice on the matter but a leaked recording suggests its own lawyers have advised that Israel has breached international humanitarian law in Gaza.