Tens of thousands of people took to the streets in Turkey's four biggest cities on Sunday and clashed with riot police firing tear gas on the third day of the fiercest anti-government demonstrations in years. The unrest erupted on Friday when trees were torn down at a park in Istanbul's main Taksim Square under government plans to redevelop the area, but widened into a broad show of defiance against the Islamist-rooted Justice and Development Party (AKP).