The European Union's chief Brexit negotiator Michel Barnier tweeted Sunday that talks with Britain over a post-Brexit trade deal were at a "crucial moment", stressing the negotiations were in full swing.
"The EU remains committed to a fair, reciprocal and balanced agreement. We respect the sovereignty of the UK. And we expect the same," he stressed, arguing both parties "must have the right to set their own laws and control their own waters".
The head of the European Commission's Task Force for Brexit stressed the importance of the UK and the bloc being equally able to act "when our interests are at stake".
The EU and the UK are "widely expected" to wrap up Brexit trade deal talks "one way or another" before Christmas, but a no-deal scenario is still on the table, a number of UK government sources told the Daily Mail.
Downing Street is ostensibly disappointed by Michel Barnier's ultimatum with regard to the fisheries issue - something that was described as something that would potentially enable Brussels to slap "lightning tariffs" on London should it put curbs on the bloc's access to UK fishing waters.
Late last week, Boris Johnson and European Commission President Ursula von der Leyen agreed to extend negotiations on the UK-EU trade deal beyond the self-imposed 13 December deadline.
Trade talks have been stuck for months over wide divergences over fishing quotas, the so-called level playing field — a set of commonly accepted rules designed to prevent businesses in one country from undercutting their rivals in others — as well as governance issues.
If no trade deal is inked before 1 January, the World Trade Organisation's rules will take effect starting in 2021, including customs tariffs and full border checks for UK goods travelling across the English Channel.