The renegotiation deal David Cameron struck with other EU leaders is not legally binding, according to his cabinet colleague and friend Michael Gove.
Mr Gove, who is campaigning for Britain to leave the EU, said the deal could be overturned by the European Court of Justice. But Downing Street rejected the Justice Secretary’s claims, saying the agreement had “legal force”.
It is Mr Gove’s first major intervention in the referendum campaign since backing Brexit and coincides with an article written by his wife Sarah Vine, in which she says he found it “agonising” reaching a decision on the deal negotiated by Mr Cameron, who is a close friend.
The Prime Minister wants Britain to remain in a reformed EU, but almost half of his parliamentary party is opposed. A referendum on Britain’s membership of the EU will be held on 23 June.
Mr Gove told the BBC: “The facts are that the European Court of Justice is not bound by this agreement until treaties are changed and we don’t know when that will be.
“He (David Cameron) is absolutely right that this is a deal between 28 nations, all of whom believe it. But the whole point about the European Court of Justice is that it stands above the nation states.”
Ms Vine said in her Daily Mail column that her husband had been “locked in an internal struggle of agonising proportions” over his decision on the referendum, but had chosen his “own heartfelt beliefs” over “loyalty to his old friend, the Prime Minister”.
A No. 10 spokesman said: “It is not true that this deal is not legally binding. Britain’s new settlement in the EU has legal force and is an irreversible international law decision that requires the European Court of Justice to take it into account.”
Former attorney general Dominic Grieve told BBC Radio 4’s Today programme: “It is fanciful to say that the agreement that the Prime Minister has arrived at does not have a force in law.”
Despite Mr Gove’s intervention, Mr Cameron’s campaign received support from a group of former senior military commanders, who warned in a letter to the Daily Telegraph that leaving the EU could adversely affect Britain’s ability to tackle threats such as the so-called Islamic State (also known as Daesh) or Vladimir Putin’s Russia.
The letter, whose signatories include former chiefs of the defence staff Field Marshal Lord Bramall and Field Marshal Lord Guthrie, says: “Europe today is facing a series of grave security challenges, from instability in the Middle East and the rise of Daesh, to resurgent Russian nationalism and aggression.
“Britain will have to confront these challenges, whether it is inside or outside the EU. But within the EU, we are stronger.”