Central authorities in China are carrying out a sweeping corruption investigation targeting the country's telecom operators, including China Mobile, China Unicom and China Telecom.
More than 60 people, including government officials and telecom employees, are under investigation for alleged corruption.
China's anti-corruption body the Central Commission for Discipline Inspection has sent agents to the three network operators to investigate mid-level executives and above.
The executives have been asked to hand over their passports during the investigation.
The investigation is set to continue.
