Officials announced Friday that 521 of the 538 persons detained during the May Day clashes have been freed from custody.
On Thursday, there were a series of clashes between workers and police in central Istanbul as authorities sought to enforce a ban on holding May Day events in Taksim Square.
On Friday, Labour and Social Security Minister Faruk Celik said that the relevant authorities needed to explain why what was apparently excessive force was used to block union members from gathering in Taksim.
