The regulator ordered the nation's phone operators, including China Mobile, China Telecom and China Unicom, to eliminate all illegal charges on their systems in the next six months.

Complaints by handset users rose 13 percent last year because of fees charged for text-message services they either didn't want or hadn't realized they were using, according to an earlier report by the China Consumer Association.

In the first quarter, the MII investigated 541 content providers and stopped 89 services, involving transactions valued at 4.3 million yuan (US$536,000), the report said.

For example, some users were charged after sending a reply to a text message from an unknown number.

Among the other scams were messages saying, "I am going to leave Shanghai tonight. Do you still remember me? Please call me immediately."

Phone users who took the bait were charged 2 to 5 yuan when they called the number, and the fees were split between the third-party service provider and the telecom.

Under the new campaign, telecom are required to publicize charges for services such as downloading ring tones and songs. In addition, the operators were ordered to check their add-on service partners in the next two months and report illegal activities to authorities by August 20. In the second phase of the campaign, the MII will send out special teams nationwide to supervise enforcement.

Shanghai is already moving ahead on its own to combat the problem.

"We carry out our own checks frequently, and we have stopped partnership with several companies providing problematic services," said Zhang Chunmin of Shanghai Mobile.