Reaching a deal on Greece's emergency financing will be possible at the technical level, but a political agreement with the country's new leftist-led government will be "very difficult" the chairman of euro zone finance ministers said on Thursday.

"I am optimistic that we will have an outcome on the technical process because I think that is a matter of simply comparing different measures and content of the program (and Syriza's program)," Jeroen Dijsselbloem told reporters as he left an EU leaders summit.

"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," he said.