Telecom frauds using personal information stolen from smartphones have been rising steadily in the world's biggest handset market, Internet firm Tencent Holdings Ltd warned on Tuesday.

The huge network of illegal mobile signal sender/blockers in big cities - they are known as pseudo base stations - are the prime reason for the sudden outbreak of tech-savvy crimes, investigators said.

More than 11 million smartphones were infected by mobile viruses sent from the pseudo base stations in the first six months of the year, according to Tencent, which is helping the police monitor online crimes.