The Beijing government is offering hefty cash rewards for information on foreign spies, state media report.
Residents of the Chinese capital can earn up to 500,000 yuan (£58,000; $72,000) by submitting tip-offs.
City officials said the public should help “to slowly construct an iron Great Wall in combating evil and guarding against spies.”
Authorities launched an awareness campaign last year, including warnings against being seduced by foreign spies.
The new regulation was announced by the security branch of the Beijing municipal government and said that residents can file tip-offs through the hotline launched last year, in person, or by post.
The cash rewards range from 10,000 to 500,000 yuan, depending on how useful the tip-offs are in “preventing or stopping espionage behaviour, or cracking espionage cases”, according to several state media outlets including Beijing Daily.
Authorities said that as the heart of Chinese governance and innovation, Beijing “is the first choice among foreign spy agencies and others who are fiercely carrying out infiltration, subversion, division, destruction and theft”.
Authorities said that in January, a group of fishermen in Jiangsu province found an “unidentifiable object inscribed with foreign words” while trawling for fish, and handed it in to authorities.
The object was later found to be “a spying device that was collecting data on China”.