TBUCHAREST (AFP) - European Union chief Donald Tusk warned Monday there was a "real" danger of the 28-nation bloc breaking up over so-called Brexit and called for greater EU coordination to address the risk.
"This is a critical moment. It is high time we started listening to each other's arguments more than to our own," he said during a visit to Romania to discuss Britain's continued membership of the EU.
"It is natural in negotiations that positions harden, as we get closer to crunch time. But the risk of break-up is real because this process is indeed very fragile.
"Handle with care. What is broken cannot be mended," he added in Bucharest, a stop on a tour of key EU capitals in a final push for a deal at a crucial Brussels summit.
Many of Prime Minister David Cameron's demands for reforms ahead of a referendum on Britain's membership of the crisis-hit bloc still face opposition just days before the meeting on Thursday and Friday.
Tusk cleared his diary in the run-up to the summit for last-ditch talks in Berlin, Paris, Athens and other capitals to press key leaders for an agreement despite what he called a "very fragile" situation.
If Britain becomes the first country to leave the EU it would further inflame a firestorm of problems so perilous that Tusk warned recently that the situation felt like "the day before World War I".
"At stake is the United Kingdom's membership of the EU. A question which only the British people can and will decide," Tusk said in Bucharest on Monday.
"At stake is also the future of our European Union, where we will all have to decide together, and where we cannot and will not compromise on the fundamental freedoms and values."