EU leaders have urged the British parliament to vote for the Brexit deal, as they expressed sadness about the UK’s impending departure.

Arriving at a special EU summit in Brussels, the bloc’s chief negotiator, Michel Barnier, delivered a veiled warning to MPs to vote for the deal, suggesting that a “no” vote could damage negotiations on the future relationship.

“Now it is time for everybody to take their responsibilities, everybody,” he said. The deal was “a necessary step to build the trust between the UK and the EU” to build “an unprecedented and ambitious future partnership”.

The EU is keenly aware that the British parliament could reject the deal.

The Dutch prime minister, Mark Rutte, helped set the tone. “You know I hate [Brexit] but it is a given,” he told reporters. “No one is a victor here today, nobody is winning, we are all losing.”

Urging British MPs to vote for the deal, he said there was nothing better on offer. “This is the max we can all do. If I would live in the UK I would say yes to this, I would say that this is very much acceptable to the United Kingdom,” he said, because the deal “limited the impacts of Brexit while balancing the vote to leave”.

Theresa May “has fought very hard”, he said, and now there was “an acceptable deal on the table”.

The prime minister was due to meet the 27 other EU leaders on Sunday morning, after the group sign off the Brexit withdrawal agreement and political declaration.

Donald Tusk, the European council president, who convened the meeting, said he was recommending EU leaders approve the outcome. “Although no one will have reasons to be happy on that day, there is one thing I would like to stress: at this critical time, the EU27 has passed the test of unity and solidarity.”

He tweeted some lyrics from the Queen singer Freddie Mercury:

As a motto for tomorrow, the words of Freddie Mercury, who passed away exactly 27 years ago: "Friends will be friends, right till the end". — Donald Tusk (@eucopresident) November 24, 2018

Arriving at the summit, Lithuania’s president, Dalia Grybauskaitė, said: “We have a summit not with British parliament but we have a summit between us and we are going to agree on the withdrawal agreement and then it will be for Britain to decide what do do next.”

EU leaders see the summit as a sombre moment. “There is nothing good for any side because it is withdrawal from the European Union,” added Grybauskaitė.

The European parliament also has to give its consent to the deal, which is expected in January, according to its president, Antonio Tajani. “We will vote for the agreement, there is a majority in favour. This is a message to our friends in the British parliament, this is a good agreement for both.”