David Cameron has issued tough new curbs on Cabinet ministers who want to support the UK quitting the EU.
In a bid to avoid the row that engulfed Labour over Hilary Benn's Syria speech - where he contradicted his party leader in Parliament - the Prime Minister has told his Cabinet they will not be able to campaign for a Brexit until after the negotiation process is complete.
HuffPost UK understands that ministers will be allowed to express their personal view either for or against EU membership from the frontbench, but will have to defend specific Government policy.
Cameron called for ministers on both sides to "treat each other with appropriate respect and courtesy" in a memo setting out the "wholly exceptional" rules which will allow members of the Government to support Brexit once the talks have finished.
The "special arrangement" will allow individual ministers to take a different position from the official Government line after a Cabinet discussion, which will follow the conclusion of talks between Cameron and his fellow EU leaders.
The Prime Minister hopes to strike a deal on his demands at a crunch summit in Brussels next month which will then allow him to recommend that the UK remains within a reformed EU, but until the talks are concluded he stressed that all his ministers should follow the Government line.
According to The Press Association, the Prime Minister sent a note to ministers saying: "Until that point - when it will become clear whether a deal can be negotiated that delivers the objectives I have set out - all ministers should continue to support the position set out in our manifesto and say or do nothing that will undermine the Government's negotiating position."
Officials would be expected to support the Government's stance and "it will not be appropriate or permissible for the civil service or individual civil servants to support ministers who opposed the Government's official position".
But ministers who oppose the official position would be able to draw on personal help and advice from their special advisers, known as 'Spads', as long as it is in line with their wishes and "in their own time".