Mobile carrier NTT Docomo said Tuesday five new smartphone models will allow investigative authorities to track the phones' locations without users being aware of it.

A spokesman said the company has already been providing such data in some circumstances, mostly relating to crime investigations.

"If requested, we provided positional information using the GPS systems on phones to emergency services such as the police, ambulance services and the Japan Coast Guard, in line with proper guidelines," the spokesman told The Japan Times.