Protesters challenge the ban on city demonstrations
Despite the Turkish government's ban on demonstrations in Taksim Square in central Istanbul, unions and opposition activists say they will converge there for May Day rallies.
Taksim Square has been the scene of anti-government protests since the summer of 2013.
Around 20,000 policemen are expected to deployed in and around the area on Thursday.
Selin Girit reports from Taksim Square.
01 May 2014