China will offer citizens as much as $15,000 in cash for reporting threats to "national security", state media reported, in Beijing's latest move to whip up fears of external foes.

Citizens offering information that leads to the discovery of "acts endangering national security" could be rewarded as much as 100,000 yuan, depending on their role in preventing or solving a case, according to the guidelines.

They may also be given "rewards in spirit," the reports said Tuesday, including in the form of certificates.

The Chinese government has for years offered monetary rewards for information on security breaches, but a new guideline issued this week by the Ministry of State Security seeks to standardise the practice, the state-owned Legal Daily reported.

The measure is "conducive to fully mobilising the enthusiasm of the general public to support and assist in national security work, widely rallying the hearts, morale, wisdom and strength of the people," a ministry representative told Legal Daily.

Beijing has increasingly encouraged the public to be vigilant against perceived national security violations, including teaching children to be on the lookout for supposed threats to the country.

State broadcaster CCTV in April published a series of infographics asking readers to be alert for spies in their midst, describing "eight faces of spying" including people posing as romantic partners and plant lovers.

China has also used national security as a justification for detaining foreign nationals during times of diplomatic tension with the detainees' home countries.

Australian journalist Cheng Lei was detained in 2020 on suspicion of national security breaches, and could face life imprisonment if deemed to have committed serious violations.

Weeks before Cheng disappeared, Australian authorities raided the homes of Chinese state media journalists as part of a foreign interference probe.

The timing of her detention and the lack of clarity about the charges against her led to speculation that the case was politically motivated or a tit-for-tat retaliation.

Months after Cheng's disappearance, Chinese authorities also detained Bloomberg News employee Haze Fan -- a Chinese citizen -- on allegations of endangering national security.

Another Chinese-born Australian, writer Yang Jun, has been accused by Beijing of espionage and is facing a trial that started last year behind closed doors.

In semi-autonomous Hong Kong, a national security law imposed in 2020 was used to stamp out dissent after widespread and sometimes violent pro-democracy protests rocked the city the year before.