Istanbul's Bosphorus Bridge and Fatih Sultan Mehmet Bridge were both closed on Friday, local television channels reported, without giving a reason.

Dogan News Agency footage showed cars and buses being diverted. CNN Turkey showed two military vehicles and a group of soldiers lined up at the entrance of one of the bridges in Turkey's biggest city.

A Turkish official who did not want to be named said soldiers had been deployed in other cities in Turkey, but did not specify which ones.

Dogan News Agency reported the national police directorate summoned all police to duty in Ankara.