Li Shuang often ignores messages sent to his cellphone.

"I get at least 10 spam messages every day. Some have investment advice or inform me that I have won a big prize. Some even suggest prostitutes are available. All are annoying," said the 25-year-old, who works in a Beijing finance company.

But legal loopholes are hampering efforts to tackle the scourge, and legislation must be enacted to close it, experts said.

The Ministry of Industry and Information Technology launched a campaign in September, in cooperation with telecom giants, to target spam, but the real problem lies with so-called base stations, which can be legally purchased.

The campaign revealed that more than 60 percent of spam was sent via base stations, allowing the senders to deliver what, at first glance, seem to be authentic messages.

Police in Henan and Guangdong provinces were able to target some stations, but said legislation needs to be enhanced, with stricter penalties, to act as a deterrent.

While the ministry will issue new rules on text messages this year, experts said the key to ensuring information security lies in improved legislation.

Members of the public can buy base stations online for less than 10,000 yuan ($1,630), a specialist on the front line of the battle against spam said, adding that any base station can send more than 10,000 messages an hour.

Lou Tao is a director of the quality management division at the Information Security Center in Luoyang, Henan province. The center was established by China Mobile in 2012, and plays an important role in reducing spam.

More than 2,700 center employees dealt with message complaints and shut down 22.27 million mobile phone numbers that sent spam last year, the company said.

Since the center was established, complaints about spam have decreased by 84 percent and the center can block 900 million pieces of spam monthly, the company added.

"But it’s difficult to block spam from the base stations because they can send a message without using our network," Lou said. "The station can imitate any number, and size is not a factor, so people can send spam even from a car."

All that is required for a base station is a connected computer.

Chen Xiaoxing, general manager of China Unicom’s Luoyang branch in Henan, said about 30 percent of complaints regarding spam were attributed to base stations.

"We opened several reporting channels, such as micro blogs and websites, for residents to complain and give us information, but spam is still a problem," he said.

More must be done to target the base stations, said Xu Qiang, an official from the market management bureau of the telecommunication administration under the ministry.

This requires coordinated efforts involving other authorities, including the police, Xu said.

Under current legislation, fines for sending spam are 5,000 yuan at most, and spam senders could be detained for up to 10 days, said Wang Xinhua, a police officer in Luo-yang.

"The punishment is not exactly harsh," Wang said.

"Most spam involves advertising, not promoting fraud or offering sexual services, so spam senders are penalized under legislation concerning interfering with radio transmissions," he added.

The ministry is calling for heavier punishment, especially for those selling base stations, Xu said.

Zhang Yanbin, a ministry engineer, said legislation must also define what spam is.

While it is illegal to send commercial information randomly in batches to thousands of people, the exact legal definition of commercial information is still vague, he said.