Turkey’s prime minister, Recep Tayyip Erdogan, has told people not to mark the anniversary of national protests that left eight dead and thousands wounded last year.
Turkish authorities deployed at least 25,000 police officers and 50 water cannon trucks and armoured vehicles to prevent would-be demonstrators from reaching Gezi Park, which was the centre-point in last year's protests.
"One year later, people, including so-called artists, are calling for demonstrations, but you, Turkey's youth, you will not respond to the call," Erdogan told an Istanbul crowd on Friday.
"These terrorist organisations manipulated our morally and financially weak youth to attack our unity and put our economy under threat," Erdogan said.
But hundreds of activists mobilised for demonstrations in Istanbul and other cities, defying the heavy police presence, AP news agency reported.
What began last May as a peaceful demonstration against plans to redevelop Gezi Park, a part of Istanbul's Taksim Square, spiralled into massive protests spread around the country against Erdogan that resulted in brutal police retaliation.
The demonstrations continued for weeks, leaving eight people dead and thousands wounded.
Despite a government ban on gatherings at Taksim Square, a symbolic rallying point, activists asked the public to hold demonstrations there.
Turkish media reported that thousands of police officers, water cannons and armoured vehicles would be deployed on May 31 to prevent demonstrators from reaching the square.
Reuters news agency reported that Turkish police had shut Gezi Park on Saturday, with riot police monitoring the perimeter of Gezi and hundreds of plainclothes officers patrolling Istiklal, a major shopping street near the square.
Kemal Kilicdaroglu, the leader of the main opposition Republican People's Party (CHP), on Friday urged the authorities to let people peacefully protest.
"Let the young people protest as they want. They are peaceful, they cannot harm anyone. What will you achieve with all these bans?" he said.
In its 12 years in power, Erdogan's Justice and Development Party(AKP) has achieved economic success, transforming a crisis-hit economy into a growing one.