Trade unions in Turkey have joined demonstrators who are calling on Prime Minister Recep Tayyip Erdogan to step down.On Wednesday, labor unions started a protest rally from Istanbul’s Sisli neighborhood towards the city’s iconic Taksim Square. Since Friday, tens of thousands of anti-government demonstrations have been held in Istanbul, Ankara, Izmir, Mugla, Antalya, and many other cities and towns. The unrest in Turkey began after police broke up a sit-in which was held in Taksim Square on May 31 in protest against the planned demolition of Gezi Park. The protesters said Gezi Park, which is a traditional gathering point for rallies and demonstrations as well as a popular tourist destination, is Istanbul's last public green space. Two major trade union confederations went on a two-day strike from Tuesday. The strike, which involves 600,000 union members, is a major public support for the protesters who are standing their ground despite police harsh crackdown. At least four people have been killed and more than a thousand injured since the beginning of anti-government protests in Turkey. Authorities say over 2,000 people have been also detained.