ReutersTurkish police have reportedly arrested more than 500 people and fired tear gas at May Day demonstrations in Istanbul.
Many of those arrested were trying to march to Taksim Square, which has seen a number of anti-government protests in the past.
The square, where demonstrations have been banned since 2013, was sealed off by police overnight.
Turkey sees significant police deployments on 1 May each year, when marches led by workers and unions are held as part of International Labour Day celebrations in many countries.
The CHD lawyers' group, which was at the rallies, said there had been more than 500 arrests.
In Ankara, several groups gathered in Tandogan Square.
Celebrations are going ahead in Kadikoy and Kartal, after they were permitted by the governor's office.
May Day celebrations in Izmir are taking place at Gundogdu Square, while in Diyarbakır they are being held at Istasyon Square.
Extensive security measures have been in place at the entrances to both squares since early Friday morning.
Trade unions filled rallies in many cities, from Bursa to Corum.
A large number of people who wanted to gather in the Mecidiyekoy district of Istanbul were surrounded by police.
The president of the Turkish Workers' Party, Erkan Bas, was among groups in Mecidiyekoy that breached the police barricade and were dispersed with water cannons and tear gas.
Bas said in a statement that blocking access to Taksim Square was "illegal" and called for it to be opened.
Turkey's President Recep Tayyip Erdogan, posted on X: "I congratulate all our worker brothers and sisters who earn their living through their labor and create added value for their country and nation on May 1st, Labor and Solidarity Day, and I send my greetings and love to all workers, employers, and employees throughout our country."
