Theresa May has urged EU leaders to “create a new dynamic” in Brexit talks as negotiations move to the next phase.
The UK prime minister addressed fellow EU leaders at a Brussels dinner, the day before they are expected to rubber stamp the Brexit “transition” deal.
She said the UK and EU should work on issues like Northern Ireland, trade and security with “energy and ambition”.
The European Council also agreed with the UK that it was “highly likely” Russia was behind the Salisbury attack.
Council President Donald Tusk tweeted: “There is no other plausible explanation.”
The prime minister addressed EU leaders ahead of the second day of the European Council summit, where they are expected to give their approval to the terms of a 21-month transition period after Brexit in March 2019.
Mrs May will not be present as the other leaders meet on Friday to discuss the transition period and consider approving guidelines for the second phase of negotiations.
She told them on Thursday: “We have the chance now to create a new dynamic in the talks, to work together to explore workable solutions – in Northern Ireland, in our future security co-operation and in order to ensure the future prosperity of all our people.”
She added: “This is an opportunity. It is our duty to take it and to enter into it with energy and ambition.”
The UK is set to leave the bloc on 29 March 2019, but earlier this week Brexit Secretary David Davis and EU chief negotiator Michel Barnier struck a deal that would allow for a transition period – which the UK government describes as an implementation period – until December 2020.
Under the terms of that joint legal text, the UK will be able to negotiate, sign and ratify its own trade deals, while EU citizens arriving in the UK will enjoy the same rights and guarantees as those who arrive before Brexit.
To the dismay of some of Mrs May’s Conservative MPs, the UK will effectively remain in the Common Fisheries Policy until the end of 2020, while a solution to avoid a hard border on the island of Ireland has yet to be agreed.
The EU is insisting on a “backstop” option of Northern Ireland effectively remaining in the customs union and parts of the single market.
Mr Tusk said on Thursday he was “absolutely sure” the two sides would find a last solution to prevent the return of physical checks on the border between Northern Ireland and the Republic of Ireland.
The Irish government has insisted the UK has provided a “cast-iron guarantee” that will ensure no physical infrastructure, checks or controls at the border after withdrawal.
A written declaration issued by the European Council on the eve of the summit called for “intensified efforts on the remaining withdrawal issues, as well as issues related to the territorial application of the Withdrawal Agreement, notably as regards Gibraltar, and reiterates that nothing is agreed until everything is agreed”.