PARIS, Nov 7 (Reuters) - French President Emmanuel Macron's government postponed a long-held target to reduce the share of nuclear energy in France's electricity generation.

French Environment Minister Nicolas Hulot told a news conference that it was not realistic to reduce the share of nuclear energy in the power mix to 50 percent by 2025 from 75 percent at present. He did not set a new deadline.

"We will reduce the share of nuclear in the mix as soon as possible," he said, adding that doing this in a hurry could endanger the security of power supply as well as targets to reduce France's CO2 emissions.

He also said that the Fessenheim nuclear plant, France's oldest, would be closed during Macron's five-year term. (Reporting by Geert De Clercq and Michel Rose; Editing by Sudip Kar-Gupta)