Turkey will more than double the number of police officers on duty in Istanbul to 37,000 and ban public celebrations in key districts on New Year's Eve for security reasons, a year after a gunman killed 39 people in a nightclub, officials said.
State media said police had also detained dozens of people for suspected membership of the Islamic State though the arrests were not linked to New Year security preparations.
On New Year's Eve a year ago, a man with an assault rifle shot dead Turks and visitors from several Arab nations, India and Canada at the exclusive Reina nightclub.
A year on, 37,000 police officers and some 4,000 gendarmes who maintain security in rural areas would be on duty over New Year, Istanbul governor Vasip Sahin told reporters on Thursday - more than double the usual daily deployment.
"Virtually all our teams will be on duty. We will take all possible measures in Istanbul so that our citizens can mark New Year happily in peace," he said.
Authorities either banned or cancelled public New Year's Eve celebrations in the central Istanbul districts of Beyoglu, Sisli and Besiktas due to security concerns, officials and media said.
Sisli municipality said it cancelled a four-day event due to start on Thursday after the local governor requested it be curtailed for security reasons. Besiktas council was refused permission to stage an event, Haberturk newspaper said.
It said security was also being tightened in Taksim square, reportedly one of the initial sites the gunman last year planned to attack before he decided to target the nightclub.
"New Year (security) measures will be at the highest level. There won't be any celebrations," Haberturk cited Beyoglu police chief Ismail Kilic as saying. "Gatherings will not be allowed."
ISIS claimed responsibility for the nightclub shooting, one of a series of attacks believed to have been carried out by the jihadists and Kurdish militants. A trial of suspects in the Reina attack, including the gunman, began this month.
Turkish police on Thursday detained 38 people, some of them Syrian citizens, for suspected Islamic State membership in an operation in the northwestern province of Bursa, the state-run Anadolu news agency said.
In raids across Istanbul on Wednesday, police detained six Islamic State-associated foreign nationals believed to be planning an attack, a police statement said.
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