New York, Mar 30 (IANS): New York city will launch a free smartphone app to protect its residents from internet hackers, Mayor Bill de Blasio has announced.

NYC Secure will alert users to suspicious activities online and warn them about potential threats on their devices, reports Xinhua news agency.

"New Yorkers aren't safe online. We can't wait around for other levels of government to do something about it or the private sector," de Blasio said on Thursday.

He said the programme, which will cost the city about $5 million a year, will operate under a "strict privacy policy" and will not collect or access any personally identifying information or transmit private data.

More than nine million New Yorkers were victims of data breaches in 2017, quadrupling the number in 2016, New York State Attorney General Eric Schneiderman announced on Thursday.

The majority of the data breaches involved Social Security numbers exposed. Those hacks accounted for 40 per cent of the 9.2 million personal records accessed illegally in 2017.

Most of the breaches were due to hacking, but 25 per cent of them were simply tied to sloppy tech practices.