Tougher measures to ensure the security of personal information are needed, legal experts said, after police detained four people accused of illegally purchasing students' family details and defrauding money from their parents.

Police say the suspects called the students' parents in Shanghai, disguising themselves as doctors and teachers, and asked them to transfer money. They were captured by police in Xiamen, Fujian province, on June 6.

Police said they also seized a list that contained the names and personal information of 400 Shanghai students.