Irish Prime Minister Micheal Martin said Thursday he has seen a positive shift in post-Brexit trade talks between Britain and the European Union but warned London must make concessions as a deadline looms. He was speaking after meeting European Council president Charles Michel, who himself warned of a "moment of truth" as both sides race to make progress before a summit of EU leaders in one week's time. "The mood appears to have changed and there's been more intensified engagement," Martin told a joint press conference in Dublin. "But mood is one thing -- it does need substance to follow the mood. One needs concrete outcomes from the negotiations, and positions need to change." The Taoiseach, Michel and European Commission president Ursula von der Leyen have all spoken to British Prime Minister Boris Johnson in recent days. Johnson has marked down the Brussels summit starting on October 15 as his deadline for a clear signal that the EU is willing to do a deal. Negotiations between the EU and UK will take place until that date and most likely later, with Brussels still hoping to come up with the outline of a deal by the end of the month. "The coming days are crucial -- this is a moment of truth," Michel said. He called for "significant steps to be made by our British friends in the coming days" on EU access to UK fishing waters, common standards and the governance mechanism of any final deal. The UK must also implement the Brexit divorce treaty signed before it left the bloc in January, he stressed, amid a row over London's attempts to rewrite sections relating to Northern Ireland. "The EU is doing its utmost to find an agreement with the UK -- but not at any cost," Michel said. EU chief negotiator Michel Barnier will meet with his UK counterpart, David Frost, in London on Friday, while negotiations will continue in Brussels early next week. Barnier on Wednesday urged member state envoys to come up with a compromise on fishing rights to present to Britain -- but said he would hold firm on state aid and governance, according to European sources. Fishing rights are a main concern for countries sharing seas with Britain: the Netherlands, Belgium, Denmark, Germany and especially France, which has taken the toughest line on the issue. "If we want an agreement, we will also need to find agreement on fish," Barnier told the envoys, according to a diplomat who was briefed on the matter. "We need a compromise that we would float to the UK as part of a total agreement," he reportedly added. In negotiations, the European side has so far insisted that its vessels would continue to enjoy unfettered access to UK waters, even after a post-Brexit transition phase that ends on December 31. But Britain wants this access limited significantly and has called for fishing rights be renegotiated every year -- a demand that the EU will refuse, sources said. Diplomats said a compromise among Europeans would require a delicate balance between member states keen to keep access to Britain's deep water fishing, and others eyeing access to coastal waters, including the Channel Islands. Barnier warned, however, that the issue should in no way divide Europeans or push them into making concessions on the other key issues, the sources said. Barnier believes the EU must "prepare itself for a reduced access to British waters," the diplomat added. csg-zap-arp-ar/phz/bmm