Swedish activist Greta Thunberg has been arrested at a climate demonstration in Brussels. The 21-year-old took part in a sit-in blockade with around 150 other activists on Saturday afternoon, according to the Belgian news agency Belga. Thunberg was detained together with more than 100 other protesters, a spokesperson for the United for Climate Justice (UCJ) campaign told dpa, before they were released on Saturday evening. The demonstrators were calling for an end to subsidies for fossil fuels. Thunberg has already been temporarily detained several times. The Swede became known worldwide for he…