Boris Johnson is in “close contact” with European Commission president Ursula von der Leyen as time runs out to strike a post-Brexit trade deal.
Sources said the pair were speaking “from time to time given there isn’t long left” until the end of the Brexit transition period next week.
The European Union’s lead negotiator Michel Barnier is due to update ambassadors from the 27 European Union nations on the state of the negotiations with the UK.
The EU’s chief negotiator will also brief MEPs as efforts continue to reach an agreement with the UK before the current trading arrangements expire on December 31.
The Prime Minister has continued to insist the UK will “prosper mightily” without a deal, despite warning that it could add further damage to an economy already ravaged by coronavirus.
The UK leaves the single market and customs union on December 31 and will face tariffs and quotas on trade with the EU unless a deal is reached.
But talks in Brussels remain difficult, with “significant differences in key areas”, including fishing rights and rules on maintaining fair competition.
Mr Johnson spoke to European Commission chief Mrs von der Leyen on Monday, according to Politico, although No 10 would not publicly confirm the call or what they discussed.
Downing Street insiders flatly rejected reports that there has been a breakthrough in the row over quotas.
Reports suggested the UK had offered a cut of around a third in the amount of fish EU vessels catch in British waters over a five-year period.
That is down from an initial demand to cut it by 60% over three years but the compromise was reportedly rejected by Brussels.
A Number 10 insider described the reported compromise as “bollocks” and officials have warned that significant differences remain between the two sides.
Mr Barnier will update EU ambassadors at 3pm GMT before addressing MEPs at 5pm.
At a press conference on Monday, Mr Johnson said the position is “unchanged” and insisted the UK will thrive without a deal, relying on World Trade Organisation terms.
“There are problems. It’s vital that everyone understands that the UK has got to be able to control its own laws completely,” he said.
“And, also, that we have got to be able to control our own fisheries.
“And it remains the case that WTO terms would be more than satisfactory for the UK.
“And we can certainly cope with any difficulties that are thrown in our way.
“Not that we don’t want a deal, but WTO terms would be entirely satisfactory.
“Prosper mightily remains an extremely good description of life after January 1 either way.”
The Office for Budget Responsibility has forecast that a no-deal outcome could result in a 2% hit to gross domestic product – a measure of the size of the economy – in 2021.
That would equate to around £45 billion being wiped off the value of the UK economy.