China's highly secretive civilian spy agency has launched a public account on a major social media platform to call on "all members of society" to join its fight against espionage, offering rewards and protection for those who provide information.

The Ministry of State Security oversees intelligence and counterintelligence both within China and overseas. Its remit has encouraged analogies to a combined CIA and FBI, but is far more secretive about its work -- without even a public website describing its activities.

But on Monday it launched an account on WeChat, the hugely popular social messaging app that boasts more than 1 billion users. A day later, the account published its first post.

Titled "Countering espionage requires the mobilization of all members of society," the ministry said national security bodies should keep reporting channels, such as hotlines and online platforms, open to handle reports of suspected espionage within China in a timely manner.

"Enhance the mechanism for reporting espionage by legally commending, rewarding and protecting individuals and organizations who report espionage," it added, "so as to normalize the mechanism for the people to participate in counter-espionage work."

It also said it is the mission of "national bodies, civic groups and commercial enterprises" to implement anti-espionage measures, adding that the government and "heads of industries" should take responsibility.

For years, Chinese authorities have encouraged the public to inform on suspected foreign spies and their Chinese collaborators through propaganda and incentive campaigns.

But those efforts have gathered pace under Xi Jinping, China's most assertive and authoritarian leader in a generation who has made state security his top priority.

Officials and state media have long pushed the narrative that China is under grave, constant threat from "hostile foreign forces," who are supposedly seeking to infiltrate and undermine the country, a message that has been further turbocharged as relations with Western powers have soured.

Counter-espionage law expansion

The security ministry's debut WeChat post cited new amendments to a counter-espionage law passed by China's rubber-stamp legislature earlier this year, which came into effect on July 1.

It said news outlets, broadcasters, television stations, the culture sector and internet providers should also take part in anti-espionage education.

China passed a sweeping counter-espionage law in 2014, which some experts said was already "ambiguous and powerful". But it updated the law in April to cast a wider net.

The latest amendments expanded the definition of espionage from covering state secrets and intelligence to any "documents, data, materials or items related to national security and interests," without specifying specific parameters for how these terms are defined.

Cyber attacks targeting China's key information infrastructure in connection with spy agencies are also categorized as espionage under the new changes.

The move has sparked worries among analysts over its potential impact on foreign companies, journalists and academics, which could face further legal risks and uncertainty for their work.

Before the law came into effect earlier this year, Chinese authorities closed the Beijing office of Mintz Group, an American corporate due diligence firm, and detained five local staff.

US consultancy Bain & Company also said in April that Chinese police had questioned staff at its Shanghai office.

Meanwhile, Japan has demanded the release of a Japanese employee of Astellas Pharma who was detained in Beijing in March for suspected espionage.

Previous anti-spying drive

There have been multiple previous calls by China for the public to look for potential spies.

In June last year, China announced "material rewards" of up to and above 100,000 yuan ($15,000) for tip-offs about people who endanger national security.

For those who came forward with less significant intelligence, authorities will present them with "spiritual rewards" in certificates instead.

A campaign in 2016 famously used a 16-panel comic book-style poster found all over the capital of Beijing.

The poster told the fictional tale of a young female civil servant -- Xiao Li or Little Li -- who was wooed by a red-haired foreigner posing as a visiting scholar.

The scholar, named Dawei or David, showered her with compliments, roses, fancy dinners and romantic walks in the park, and convinced the woman to provide him with internal documents from her government propaganda workplace.

The story ended with Xiao Li being taken away by security officials and discovering that her boyfriend was a foreign spy.