Prime Minister Theresa May urged the EU to "step forward together" with Britain on Friday as the bloc's leaders hoped she would finally offer a compromise to reach a Brexit divorce deal in December.
The embattled British premier was set to meet EU President Donald Tusk on the sidelines of a summit with ex-Soviet states in Brussels in a bid to unlock negotiations on a future trade deal.
EU officials were increasingly hopeful she would bring a new proposal on the thorny issue of Britain's exit bill, after senior British ministers agreed earlier this week to improve the offer to a reported 40 billion euros.
Arriving in Brussels, May refused to deny she was ready to bump up the amount Britain would pay when she meets Tusk at 1530 GMT, but insisted any such move must be tied to a final deal on future relations next year.
"These negotiations are continuing but what I'm clear about is that we must step forward together. This is for both the UK and the European Union to move to the next stage," she told reporters.
May will also meet her counterparts from Lithuania, Belgium and Denmark in Brussels.
The EU insists Britain must tie up divorce terms -- the bill, the Irish border and the rights of EU nationals living in Britain -- before there can be any talks on future relations.
At a meeting in Gothenburg a week ago, Tusk gave May until the start of December to make "much more progress" in order to unlock trade negotiations at an EU summit on December 14-15.
European Commission President Jean-Claude Juncker appeared more optimistic than previously about a deal but said nothing would be decided before he had dinner with May on December 4.
"Yes," he replied in English when asked if he was confident of a deal.
"The actual final phase begins on December 4. There is some movement, I don't know in which direction, but I hope in the right direction," the former Luxembourg prime minister added in German.
But Ireland remains a sticking point, with Dublin stepping up threats to veto a deal if its concerns about the border with British-ruled Northern Ireland are not taken into account.
"If progress isn't made in terms of more clarity and more credibility... in a way that prevents a hard border on the island of Ireland, well then we cannot move on to phase two," Irish Foreign Minister Simon Coveney said.
Coveney admitted however that a political crisis in Ireland over the deputy premier's handling of a police whistleblower case had left the government in a "precarious position".
EU member states have become increasingly impatient for Britain to meet its terms, and increasingly worried that May's fragile Conservative government is unable to do so even if it wanted to.
Britain is reportedly set to double its offer to settle its commitments to the EU budget from 20 billion to 40 billion, but the EU has so far said the true figure should be closer to 60 billion.
Failure to reach a deal at the December summit would leave little time for trade talks, which the EU wants to wrap up in October to allow time for a deal to be ratified by national parliaments ahead of Brexit Day on March 29, 2019.
May meanwhile said her presence at the so-called Eastern Partnership Summit with six former Soviet states showed that Britain was "unconditionally committed to maintaining Europe's security" despite Brexit.
The British premier also took aim at Moscow, saying Europe must be "open-eyed to the actions of hostile states like Russia which... attempt to tear our collective strength apart."