Brussels chief Donald Tusk last night warned Britain not to waste the latest Brexit extension because 'it may be the last'.

The outgoing EU Council boss issued the warning as MPs looked set to finally support a December general election that could break the Brexit impasse. The vote eventually passed by 438 to 20.

EU sources insisted his intervention was not an attempt to influence proceedings in Westminster and merely timed to coincide with the latest three-month delay officially being enshrined in law.

Brussels chief Donald Tusk last night warned Britain not to waste the latest Brexit extension because 'it may be the last'. Mr Tusk is pictured in Brussels on October 22

The EU Council boss issued the warning as MPs looked set to finally support a December general election that could break the Brexit impasse

Mr Tusk, whose term as EU Council president ends next month, tweeted: 'To my British friends, The EU27 has formally adopted the extension. It may be the last one. Please make the best use of this time.

'I also want to say goodbye to you as my mission here is coming to an end. I will keep my fingers crossed for you.'

The remaining EU27 leaders formally signed off on the so-called 'flextension' yesterday via written procedure, delaying Brexit until January 31.

However, it also gives Britain the option to leave by December 1 or January 1 if Boris Johnson's Brexit deal is ratified before the deadline.

Although EU diplomats privately admit the UK is likely to be granted another extension beyond January 31 if it needed and asked for one, they say the terms and length of any further delay could hinge on how well Britain uses this one.

One EU diplomat said: 'Britain already has this extra time that it asked for. It is important to use it well.' Sources also point out that Mr Tusk's successor, former Belgian prime minister Charles Michel, is a hardliner when it comes to extensions.

Meanwhile, the EU's chief negotiator, Michel Barnier, last night gave Mr Johnson a boost with positive comments about a basic free trade deal. He is pictured in Brussels on October 28

Mr Tusk has been lenient over delays, even suggesting an extension of a year before the UK was eventually given an extra six months until October 31 earlier this year.

But Mr Michel, who will take over as EU Council president on December 1, took a hardline while he was Belgian premier, similar to that of French president Emmanuel Macron.

Both demanded strong justifications for any extensions, threatened to use their vetos and favoured much shorter delays to keep pressure on Britain.

Senior diplomats and officials in Brussels believe the EU could 'technically' grant further extensions until June next year, but that after this it becomes 'politically' tricky.

Boris Johnson arriving at Downing Street after last night's general election debate

This is because the bloc is likely to have signed off its next budget cycle, which runs from 2021-2027, by next summer and will be unable to plan properly if the UK is still a member state.

Meanwhile, the EU's chief negotiator, Michel Barnier, last night gave Mr Johnson a boost by saying that, even if Britain does not leave until January 31, a basic free-trade deal could be done in the eleven months before the transition period ends on December 31, 2020.

This would allow Britain to avoid a 'cliff-edge' at the end of next year, which some MPs have raised concerns about and said means they could not vote for Mr Johnson's deal.

Until the end of 2020, the UK will stay in the EU's single market and customs union under the terms of the transition period.

In an interview with the Guardian Mr Barnier said it would be possible to negotiate 'the principle elements' of a free-trade agreement to avoid the potential economic cliff edge at the end of 2020.

However, other areas of the future relationship such defence cooperation, transport and security would take much longer.

'We cannot do everything in 11 months, we will need more time,' he said.