By Jan Strupczewski and Robin Emmott BRUSSELS (Reuters) - European Union leaders did not enter into any negotiations on Greece's economic problems on Thursday, leaving the talks to officials who are to meet on Friday, the chairman of the EU summit Donald Tusk said. "The leaders did not enter into a negotiation on Greece," Tusk told a news conference after Thursday's Brussels summit. Greece, where the anti-austerity government of Alexis Tsipras took power in January, needs money to keep it afloat while it negotiates with the euro zone on what should replace a 240-billion euro bailout scheme that expires in two weeks. Euro zone countries want Athens to ask for a technical extension of the current program to buy itself time until something else is agreed. Tsipras rejects that, arguing he won elections on promises of ending the bailout. An emergency meeting of euro zone finance ministers on Wednesday failed to produce a statement or even an agreement for euro zone and Greek negotiators to continue talks before a last-chance meeting of euro zone ministers on Feb. 16. But the president of the Eurogroup of euro zone finance ministers, Jeroen Dijsselbloem, agreed with Tsipras on Thursday to continue talks between Greek and euro zone officials to find common ground. "I am optimistic that we will have an outcome on the technical process," Dijsselbloem told reporters. But he added: "I am very cautious on the political side. It is going to be very difficult. It is going to take time. Don't get your hopes up yet." After Feb. 16, EU officials fear that even if Greece were to ask for an extension of the current program, there would not be enough time for some euro zone parliaments to approve it. Once the bailout expires on Feb. 28, Athens will lose access to euro zone or market financing and its banks will lose access to European Central Bank refinancing or the 11 billion euro EU safety cushion for their possible emergency recapitalization. Greece would also lose eligibility to negotiate more time to repay the loans it got from the euro zone. (Reporting by Jan Strupczewski and Robin Emmott; Editing by Alastair Macdonald)