Boris Johnson and the European Union’s leaders have agreed that “new momentum” is required to revive trade talks between the UK and the bloc.

The UK has called for a post-Brexit agreement to be reached by the end of the summer, but European Council chief Charles Michel said the EU would not be pressured into buying a “pig in a poke”.

Four rounds of negotiations have so far made little progress, but the two sides have agreed to an “intensified” negotiating timetable as the clock counts down to the end of the current transition period at the end of year.

The EU has formally accepted that the UK would not seek any extension to the transition which allows Britain continued access to the single market while talks continue.

In a joint statement, the two sides said: “The parties welcomed the constructive discussions on the future relationship that had taken place under the leadership of chief negotiators David Frost and Michel Barnier, allowing both sides to clarify and further understand positions.

“They noted that four rounds had been completed and texts exchanged despite the challenges presented by the Covid-19 pandemic.

“The parties agreed nevertheless that new momentum was required. They supported the plans agreed by chief negotiators to intensify the talks in July and to create the most conducive conditions for concluding and ratifying a deal before the end of 2020.

“This should include, if possible, finding an early understanding on the principles underlying any agreement.”

The EU side were represented in the summit by Mr Michel, European Commission president Ursula von der Leyen and European Parliament president David Sassoli.

Mr Michel underlined the EU’s commitment to the “level playing field” – a key demand aimed at ensuring fair competition by preventing the UK straying too far from Brussels’ rules on workers’ rights, environmental protections and state subsidies.

The Government has resisted the demand, arguing that it limits the UK’s sovereignty and goes further than conditions imposed on other countries the EU has signed trade deals with.

Mr Michel said a “broad and ambitious” agreement was in both sides’ interests but the level playing field was “essential”.

The EU was “ready to put a tiger in the tank but not to buy a pig in a poke”.