The president of the European Commission has ruled out any treaty negotiations on Britain’s relationship with Europe until two years after the referendum promised by David Cameron yesterday.

In comments that will infuriate the prime minister, sources close to Jean-Claude Juncker told The Times that there was no prospect of formal plans for treaty change until the end of 2019 at the earliest, with negotiations beginning the following year.

“No treaty change proposals are envisaged until after November 2019, the end of Mr Juncker’s mandate as president of the commission,” an official said.

Mr Cameron tried to block Mr Juncker from taking the top Brussels post last summer. The setback means he faces holding a vote on EU membership without the treaty changes that he