KATOWICE, Poland (AP) — Environmental groups attending the U.N. climate summit in Poland say at least 13 activists have been deported or denied entry by authorities. The Climate Action Network, an umbrella group of hundreds of organizations from around the world, protested the deportations Friday, calling them “extremely worrying.” It named one of those denied entry as Belgium-based activist Zanna Vanrenterghem, adding she was being held at Poland’s border with the Czech Republic. CAN said Polish authorities accused Vanrenterghem, who organized a large protest in Brussels last weekend, of being a threat to national security. A Polish border guards’ spokeswoman said she had no information about the matter. Environmental group 350.org said the other activists affected include six from Ukraine, two each the United State and Germany, and one each from Kyrgyzstan and Georgia.