Brussels - British Prime Minister Theresa May will appeal to European Union leaders at a crunch summit in Brussels on Thursday to push forward the deadlocked Brexit negotiations.At a meeting moved to a new venue at the last minute due to an eruption of toxic gas, May will urge her colleagues to start looking now at a future trade deal and a transition period after Britain leaves in 2019.The EU says that there is insufficient progress on divorce issues to move on to the next phase dealing with future relations at this summit, but that it will start internal preparations to do so in December.May will "encourage them to move the conversation on to consider the future partnership and the implementation period, so that they are ready to engage in that discussion as soon as possible", a senior British government official said.May also published a letter on her Facebook page promising to make it as easy as possible for EU citizens to stay in the UK after Brexit. The British official said a deal on citizens' rights was "within touching distance."EU President Donald Tusk warned there would be no breakthroughs at the summit, saying that while there had been "promising progress" London needed to come up with more concrete proposals."I don't expect any kind of breakthrough tomorrow - we have to work really hard in between October and December to finalise this so-called first phase and to start our negotiations on our future relations with the UK," Tusk said.Divorce talks on the rights of EU citizens living in Britain have made the most progress, while issues surrounding Northern Ireland are less far along, and the topic of the bill the EU wants Britain to pay is virtually deadlocked.'Nice words' are cheap After five rounds of negotiations produced few results, fears are growing that Britain may fail to strike a withdrawal agreement before its formal departure on March 29, 2019, which would have a major economic and social impact.Britain's exit bill is the most poisonous issue. May has promised to maintain Britain's contributions for two years after Brexit in March 2019 to complete the current EU budget period, totalling around €20bn.European Parliament chief Antonio Tajani - whose institution will have a final veto on any Brexit deal - told the BBC on that "20 billion is peanuts. The problem is €50bn- or €60bn, this is the real situation."EU diplomats said the decision to start internal preparations was designed to throw May a bone at the summit, while sticking to the French- and German-led insistence on settling the bill before starting trade talks."Writing a few nice words in the summit conclusions doesn't cost much... just 10 billion per sentence," an EU diplomat joked.The summit takes place over two days, including a special session on Brexit on Friday morning from which May will be excluded.British officials said that during Thursday's dinner May would highlight her "bold vision", building on a speech in Florence last month in which she unveiled key proposals on the financial settlement and on a two-year transition."What the prime minister wants to see is a clear commitment to swift progress from both sides, for an ambitious plan to be set out for what should be achieved in the weeks ahead," the official added.Macron trade appeal May was advised against pushing for a full discussion with EU leaders, who view Brexit as an unwelcome distraction from efforts to reform the bloc after years of crisis.On Thursday French President Emmanuel Macron will push trade onto the agenda with a call to his sceptical EU counterparts to put the brakes on free trade agreements or risk angering citizens who are increasingly wary of globalisation.The leaders will also deal with foreign affairs including Turkey, the crisis over North Korea's nuclear weapons and US President Donald Trump's refusal to certify the 2015 Iran nuclear deal.On Friday morning Tusk will discuss an ambitious timeline of 13 summits over the next two years to reboot the EU and introduce major reforms of the eurozone.On the eve of the summit the meeting was moved from the EU's new €321m Europa headquarters, dubbed the "Space Egg" because of its futuristic looks, to an older building after a leak of noxious fumes in the kitchen made several people ill.