BRUSSELS, Dec 11 (Reuters) - A deal reached by European Union leaders in the early hours of Friday to cut EU net greenhouse gas emissions at least 55% by 2030 makes credible the more ambitious target of having zero net emissions by 2050, the head of the European Council said. A reduction of 55% by 2030 “means that our 2050 commitment is credible,” Charles Michel told a news conference on Friday, adding that reaching that deal “wasn’t easy” and required a marathon meeting of EU leaders. (Reporting by Francesco Guarascio, Robin Emmott and John Chalmers. Editing by Jane Merriman)