Turkish police on Friday arrested a man who threatened to set off a bomb outside the US consulate in Istanbul, local media reported.

The suspect was not carrying any explosives, according to initial reports, the private Dogan news agency said.

Police cordoned off the street outside the consulate after the detention of the suspect, who was described as "mentally instable," reports said.

Istanbul remains on high security alert after a female suicide bomber blew herself up in January in the Sultanahmet district -- the location of most of the biggest historic tourist attractions in the city, killing herself and a policeman.

In February 2013, a suicide bomber attacked the highly-fortified US embassy in Ankara, killing Turkish security guard. The left-wing Revolutionary People's Liberation Party/Front (DHKP/C) claimed responsibility for the attack.