By Ayla Jean Yackley
ISTANBUL, May 31 (Reuters) - Turkish police on Saturday shut Gezi Park, the Istanbul square at the centre of mass demonstrations in 2013, to prevent any efforts to mark the anniversary of the biggest anti-government protests in decades.
Prime Minister Tayyip Erdogan, who was the target of many protesters' ire last year, warned people to stay out of Taksim Square, which adjoins the park, saying security forces would do whatever is necessary to keep the area clear.
Riot police circled the perimeter of Gezi, and hundreds of plainclothes officers carrying batons patrolled Istiklal, a major shopping street that leads to Taksim as well as a popular tourist spot.
There was no sign of unrest at midday. Taksim Solidarity, one of the main organisers of last year's protest movement, called for a rally at Taksim at 7 p.m. (1600 GMT).
On May 31, 2013, police forcefully evicted environmentalists from Gezi Park who had staged a peaceful sit-in for several days to try to stop government plans to raze the green space and build a shopping mall.
Angered by the use of violence, tens of thousands of people from a variety of political backgrounds descended on Gezi and occupied Taksim Square for about two weeks before authorities finally cleared the space. Many complained of what they saw as growing authoritarianism after Erdogan's decade in office.
Six people including one police officer died in the demonstrations, which had spread to other major Turkish cities, and another half-dozen or so others have lost their lives in related protests in the ensuing months.
"Our security forces have clear orders. They will do whatever is necessary from A to Z," Erdogan said at a ceremony in Istanbul that was broadcast live by the NTV news channel.
Elif Cetinkaya, 45, and her family gathered across the street from Gezi Park on Saturday, wearing T-shirts with the images of those killed in the 2013 unrest.
"Why did so many people have to die to save this park? We are here to mourn their loss and show that we stand firm, no matter what obstacles they erect," Cetinkaya said.
Smaller demos have erupted in Taksim and other parts of Istanbul sporadically since last June but none have been near the scale of the first two weeks of protests at the square.
The protest movement appeared to have little impact on the ruling AK Party's political fortunes when it handily won national municipal elections in March.
But Gezi Park remains a park, one of the few green spaces in central Istanbul, Europe's biggest city.
Newspapers said 25,000 officers had been deployed on Saturday. Police thronged the residential district of Cihangir, relaxing in parking lots and at cafes as a light rain fell.
The metro station at Taksim was also closed to travellers, as were boulevards that lead to the square.
Ferryboat services between Istanbul's shores on either side of the Bosphorus Strait were also cancelled on orders of the governor's office, the city ferry line said on its website. (Editing by Mark Heinrich)