An anti-graft campaign targeting China's largest telecom service provider, China Mobile, has been expanded as another senior executive was allegedly placed under investigation, China Business News reported.

Li Xinze, general manager of China Mobile in Guangdong province, was placed under investigation on Saturday, China Business News reported. The report didn't give any reason for the alleged investigation.

Li is the 13th senior executive to have been placed under investigation since 2010, when Zhang Chunjiang, former deputy general manager of China Mobile, was found guilty of taking bribes.

In 2012, China Mobile Guangdong posted a net profit of 23.8 billion yuan ($3.86 billion), taking up more than 18 percent of the total net profit of the mobile operator.