Brussels plans to hit Britain with a demand for access to UK fishing waters the day after Brexit, it has emerged.

Sources said the plan was to make EU access to British waters a condition for any trade deal and to make the demand public on, or as close as possible, to February 1, if Boris Johnson wins a majority in the general election.

“That will be the day that reality hits home,” one EU diplomat told The Telegraph.

The European Commission began work on Monday on drawing up internal mandates for the trade negotiations that will begin once Britain leaves the EU on January 31, 2020.

British officials insist that Britain will be taking back control of its fishing waters, which are currently pooled with EU fleets, after Brexit.

Influential EU countries such as France, Denmark, Spain, Belgium and the Netherlands want to maintain the status quo, which allows UK fleets to fish EU waters, after Britain leaves.

A Tory majority would pave the way for the ratification of the Brexit Withdrawal Agreement by the House of Commons and the European Parliament, which would mean Britain leaves at 11pm UK time on January 31.

That will trigger an 11 month transition period to negotiate the UK-EU free trade agreement. The Tory manifesto promises that the tight time frame will not be extended.