Prime Minister Joseph Muscat said EU leaders would do well to take a back seat and refrain from campaigning in the UK unless invited to do so since the ball was now in the court of British voters.

However, he confirmed that he was invited for talks at Chatham House where he would be giving his views on the UK-EU deal.

Dr Muscat said the agreed deal made it clear that there was no plan B for the UK if voters rejected EU membership in the referendum.

“If British voters want out of the EU there will be no second-round negotiations for a different deal and immediately a mechanism for the UK’s exit would kick in.”

He said the deal made it clear that all member states could benefit from the special concessions agreed, a point that Malta had stressed from the outset.

He added the agreement also broke a taboo in the EU by making it clear that change was possible if countries faced specific circumstances.

"What is written can be changed and I believe this is not a bad thing but rather a new beginning for the EU because it signals greater sensitivity to what people feel."

David Cameron hailed a landmark deal last night which he said gave Britain "special status" in the European Union and pledged to campaign heart and soul to stay in the EU at a deeply uncertain referendum expected in June.

At a summit that ran into overtime, EU leaders agreed unanimously on a package of measures aimed at keeping Britain in the 28-nation bloc to avoid a potentially disastrous divorce.

Their legally binding decision granted Britain an explicit exemption from the founding goal of "ever closer union", offered concessions on the welfare rights of migrant workers and safeguards for the City of London financial centre.

The British prime minister said he had achieved all his main negotiating aims and would recommend the agreement to his cabinet on Saturday, firing the starting gun on a fierce referendum campaign on Britain's future membership of the bloc.

"I believe we are stronger, safer and better off inside a reformed European Union," he told a news conference. "And that is why I will be campaigning with all my heart and soul to persuade the British people to remain in the reformed European union that we have secured today."

The eurosceptic "Vote Leave" campaign was quick to dismiss what it called "Cameron's hollow deal" as bad for Britain.