The leaders of the European Union have called for more progress in post-Brexit trade talks in a call with British Prime Minister Boris Johnson.

The EU officials told Mr Johnson that they will pursue post-Brexit trade talks but will not make a deal at just any price.

The president of the European Council, Charles Michel, tweeted that he and EU Commission president Ursula von der Leyen had "pressed again for progress to be made at the negotiation table".

"The EU is working on a deal, but not at any price. Conditions must be right, on fisheries, level-playing field and governance. Still a lot of work ahead of us," Me von der Leyen tweeted.

In a statement, Downing Street said that Mr Johnson expressed his "disappointment" that talks with the EU have not made more progress.

In the call Mr Johnson said he will reflect on the outcome of this week's EU's summit before setting out the UK's next steps.

He has previously suggested he would walk away from the negotiating table if there was no agreement on a trade deal by the time of the two-day summit meeting in Brussels starting tomorrow.

Following the call, a No. 10 spokesman said: "The Prime Minister noted the desirability of a deal, but expressed his disappointment that more progress had not been made over the past two weeks.

"The Prime Minister said that he looked forward to hearing the outcome of the European Council and would reflect before setting out the UK's next steps in the light of his statement of September 7."

Negotiations between the EU and UK will continue over the next two weeks despite Mr Johnson's earlier assertion that this week’s EU leaders summit marks the deadline for agreement, according to a source close to the talks.

There is growing pessimism that the key stumbling blocks to a deal - such as fisheries and the so-called level playing field - can be overcome in the short term, says the source.

At a broader level, London believes the EU still does not fully accept that the UK will become an independent, sovereign country after Brexit, the source says.

This appears to be holding up discussions on fisheries, state aid, how disputes will be settled, and the ability for the EU to retaliate in different sectors if there is a dispute.

Fishing is among the stumbling blocks to a deal

It is also understood that London is insisting it will keep the clauses within the Internal Market Bill which breach the Northern Ireland Protocol on the statute books once the bill becomes law, despite the EU's insistence that no Free Trade Agreement (FTA) will be ratified unless the clauses are withdrawn.

Both chief negotiators, the EU’s Michel Barnier and David Frost on the British side, have been leading negotiations in Brussels this week.

The source confirmed that negotiations would continue over the coming weeks.

The UK continues to argue that it is simply seeking the same kind of FTA as those recently signed by the EU with other third countries, such as Canada, Japan and South Korea.

On the vexed question of state aid, and how both sides can ensure they are not undercut by the other when it comes to subsidising companies or industries, Mr Barnier has proposed a "toolbox" containing four separate measures. 

These include both sides signing up to "high level principles", the requirement for the UK to have a robust, independent competition authority, the creation of a dispute settlement mechanism, and the ability for both sides to take quick retaliatory measures that would not be limited to the imposition of tariffs on the other side's goods.

According to a source close to the negotiations, both sides are prepared to accept that overall framework, but are some way apart on the individual components.

The EU side remains downbeat on the fisheries question. A source close to the talks pointed out that if there is no overall agreement then European fleets will not be legally entitled to any fish quota at all in UK waters.

EU coastal member states, including Ireland, have taken a harder line in recent weeks on maintaining the status quo as far as possible, meaning EU fleets would continue to enjoy access to UK waters and would largely be able to catch their share of stocks which straddle both EU and UK waters as they do at present under the Common Fisheries Policy.

Additional reporting Tony Connelly