BEIJING -- Over 550 suspects involved in 90 cases of illegally registering and selling internet accounts have been detained amid a national crackdown, the Ministry of Public Security said Saturday.

The suspects illegally collected mobile numbers and other personal information of middle-aged and elderly people in rural areas on the pretext of "promoting digital medical insurance certificates," the ministry said.

During the crackdown, more than 600,000 pieces of illegally-obtained personal information were spotted, with over 40,000 illegal internet accounts seized.

A MPS official called on the public to stay vigilant, not to let strangers operate their mobile phones or scan QR codes of unknown origin.