BRUSSELS, Dec 20 (Reuters) - The European Union said on Monday a Polish law that critics say aims to silence a news channel critical of the government poses severe risks to media freedom and pluralism. Unexpectedly rushed through parliament on Friday, the legislation would tighten rules around foreign ownership of media, specifically affecting the ability of news channel TVN24, owned by U.S. media company Discovery Inc(DISCA.O), to operate. read more "We are following the latest developments with concern," a European Commission spokesperson told a news conference in Brussels. The Commission expects EU member states to ensure their policies and laws do not undermine their commitment to ensure a free, independent and diverse media sector, he said. The bill, yet to be signed into law by President Andrzej Duda, has soured ties between NATO-member state Poland and the United States at a time of heightened tension in eastern Europe over what some countries see as increased Russian assertiveness. The European Commission said it would follow developments in Poland closely as the law could lead to enforced changes of the ownership structure of media companies. "The vote that took place on Friday puts further pressure on the media sector on Poland...It may lead to limitation of media freedom in Poland where the media landscape already suffers under growing politicization," the spokesperson said, noting nationwide protests against the bill over the weekend. read more Poland"s ruling nationalist Law and Justice (PiS) party has long said that foreign media groups have too much power in the country and distort public debate. Critics say the moves against foreign media groups are part of an increasingly authoritarian agenda that has put Warsaw at loggerheads with Brussels over LGBT rights and judicial reforms.