Boris Johnson appeared unwilling to compromise in order to secure a trade and security deal with Brussels when he joined EU leaders for a summit last week, one of the three who attended the meeting has told the Guardian. David Sassoli, the president of the European parliament, punctured a recent outbreak of optimism over a potential deal by warning that the EU had been left concerned at the end of a video conference call by the lack of “enthusiasm” to find common ground on the most contentious issues. After the discussions last Monday, the British prime minister insisted he could see no reason why an agreement could not be secured with Brussels by the end of July following intensified talks. In a joint statement, Johnson, Sassoli and the presidents of the European commission and council, Ursula von der Leyen and Charles Michel, had said “new momentum was required”. But in an interview with the Guardian, Sassoli warned that he had not been imbued with confidence the prime minister was ready to do what was necessary to secure agreement before the end of the transition period on 31 December. “Together, we are very worried because we don’t see great enthusiasm from the British authorities and we don’t see a strong will to get to an agreement that satisfies all parties,” he said. “Obviously as an agreement, it has to satisfy both parties that it cannot advantage one over the other. And this puts us in a situation in which at the moment we are frankly a little bit worried.” The two sides are stuck on issues of access to British waters for European fishermen and dispute resolution in a future deal, as well as the so-called level playing field provisions, where the EU has been demanding common environmental, labour and social standards. On Wednesday, Barnier reiterated that he was willing to work on “clever compromises” in the new rounds of talks scheduled in July and August, mentioning “regulatory equivalence” as an alternative to the UK incorporating EU state aid law into domestic legislation. Sassoli said Barnier had been given the “maximum margin” of flexibility by the member states to find a compromise, but that it “takes two to tango”. “There cannot be one party that prevails,” Sassoli said. “Basically, the fact that they don’t really want to build upon the political declaration, this really does disturb us greatly, because that has to be the basis for everything for the whole negotiation,” Sassoli said, in reference to the 27-page document agreed last year on the scope of a future deal. “We reached an agreement, and it now must be respected. This really is something which concerns us at the moment.” The UK has taken a minimalist approach to the agreement in the political declaration to incorporate level playing field provisions in a treaty ensuring neither side is able to undercut the other by downgrading their standards. The UK negotiator, David Frost, has rejected any deal that sets up EU law as the common standard to meet. Sassoli said that when the EU leaders emphasised during the meeting the need for a deal that would give the European fishing fleet fair access to UK waters, he was also concerned by the prime minister’s reply. “The response that was given by the prime minister was that fishermen voted for Brexit. We want to respect their point of view, of course, but we also believe that we’re talking here about a very important resource both for the UK and for Europe, and we’re talking about the sea, so we think we can come to a common agreement on this.” The prime minister has said he will not extend the transition period, with the deadline for an agreement on extra time passing next week. Sassoli said he had personally hoped that an extension would be sought given the difficulties in negotiating the terms of the future relationship during the coronavirus pandemic. Both Barnier and Frost have been infected with the virus during the crisis. Sassoli, an Italian MEP since 2009, who was elected the president of the parliament last year, said he feared Downing Street was seeking to rush the EU into decisions by shortening the timeframe for talks. He said: “This [extension] is something that I actually hoped would happen for technical reasons, because we know that covid has cost us a lot of time in negotiation, so it could have been a very good opportunity. If this really is our goal, if we want an agreement and it would have given us a few more weeks … “I do believe that it is a way to put the European Union in a difficult position, an unpleasant position, a position in which no one is is respecting the goodwill which was initially shown to go towards agreement.”