Iran Press/ Europe: A senior UK government source said that the prospects of a breakthrough were "receding" and accused the EU of making "11th-hour" demands.
But a Brussels source denied this, with EU chief negotiator Michel Barnier calling Friday an "important day".
Mr. Barnier is staying in London for talks, rather than returning to Brussels, as planned.
Both sides have to agree and ratify any deal by 31 December, when the current rules on EU-UK trade end.
If they do not, they will do business on World Trade Organization rules, meaning the introduction of tariffs, or taxes on imports.
The negotiating teams are seeking compromises in key areas - including fishing rights and business competition rule - in time for EU leaders to discuss them at a summit scheduled for Thursday.
But European Council President Charles Michel urged the EU's 27 member states to maintain "unity" as negotiations continue.
ritain left the EU on January 30 and a post-Brexit transition period in which it still benefits from de facto EU membership will come to an end on December 31.
Without a new agreement, the two sides would see ties reduced to minimum standards set by the World Trade Organization with high tariffs and serious disruptions to business.
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