EU's Brexit negotiator Michel Barnier gives a news conference after Brexit negotiations, in Brussels, Belgium, June 5, 2020. [Photo/Agencies]

The European Union's chief Brexit negotiator, Michel Barnier, has warned the United Kingdom about trying to backtrack on points agreed in last year's political declaration after the latest round of Brexit negotiations ended with no progress made, and time running out.

The declaration of shared principles for future relations agreed between EU leaders and Prime Minister Boris Johnson was the basis of Johnson's so-called oven-ready Brexit deal, a major campaigning tool in December's general election. But now the UK is accused of wanting to change details, leading Barnier to say the EU "cannot and … will not accept this backtracking".

"My responsibility is to speak to truth and, to tell the truth, this week there have been no significant areas of progress,"he said.

"In all areas, the UK continues to backtrack under commitments undertaken in the political declaration, including on fisheries. We cannot and will not accept this backtracking on the political declaration."

Britain left the 27-member bloc at the end of January, with a self-imposed end-of-year deadline for a deal to be found covering alternatives for existing arrangements. So far the two sides have found little common ground, with the so-called level playing field of protecting business from unfair competition a particular sticking point.

"We can only take note that there has been no substantial progress since the beginning of these negotiations, and that we cannot continue like this forever," he added.

The UK has suggested accepting tariffs on some agricultural products, which risks upsetting the British farming industry, in return for demands over the level playing field being eased, but Barnier has shown little enthusiasm. "So far the idea has fallen on stony ground," the Financial Times quoted a British negotiator as saying, "but it's still in there in the discussion".

The lack of progress heaps more pressure on the summit expected later this month between Johnson and European Commission President Ursula von der Leyen.

The UK has until the end of June to ask for an extension to the transition period, which at Britain's insistence currently finishes in December. Johnson insists this will not happen, increasing the likelihood of a no-deal Brexit, but when asked about this at a Downing Street novel coronavirus briefing, Health Secretary Matt Hancock said he hoped it could be avoided.

"Our position is very reasonable," he said.

"It's that any agreement we reach must reflect the fact that the UK is an independent sovereign state. And we're working very hard and will accelerate the work to make progress in talks by the end of the year so that we can put into place the vision that has already been agreed between the UK and the EU which is based within the political declaration."

Barnier said the transition can be extended. "We have always been open to the possibility of an extension of one or two years — as is possible under the exit agreement. And our door remains open," he said.