Britain on Friday complained about a lack of movement on major stumbling blocks in post-Brexit trade talks with the European Union, after the third round of negotiations broke up.
Talks have been held all week by videolink because of coronavirus restrictions, with a deadline approaching at the end of June for Britain to request an extension.
The country left the bloc in January but remains under EU rules until the December 31 as it seeks to forge a new basis for relations.
Prime Minister Boris Johnson has categorically ruled out asking for more time for talks.
UK chief negotiator David Frost said agreement could be secured in areas such as law enforcement, civil nuclear and aviation "without major difficulties in the time available".
But he said there had been "very little progress towards agreement on the most significant outstanding issues between us", in particular the so-called "level playing field" governing open and fair competition.
He said the EU's "insistence on including a set of novel and unbalanced proposals" which would bind Britain to EU law or standards was "unprecedented in free trade agreements".
"As soon as the EU recognises that we will not conclude an agreement on that basis, we will be able to make progress," he added.
There had been "useful discussions" on another bone of contention -- fisheries.
But he also said the EU focus on full access to British waters was "incompatible with our future status as an independent coastal state".
Britain is unable to agree arrangements that were "manifestly unbalanced and against the interests of the UK fishing industry", he added.
He called for a "change in EU approach" for the next round of talks that begin on June 1.
"The UK will continue to work hard to find an agreement, for as long as there is a constructive process in being, and continues to believe that this is possible," he added.