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.