China has launched a campaign to warn people of the dangers of trusting handsome foreigners who might have secret agendas.

Titled Dangerous Love, the posters, issued to mark the first ever National Security Education Day, tell the story of a young Chinese civil servant, called Little Li, who meets a red-headed man at a dinner party.

As "David" woos her with compliments, flowers and romantic walks in the park, Li fails to realise he is a foreign spy.

The cartoons depict a scenario where Li gives David secret internal documents from her government office before they are both arrested.

"David" the red-headed man is not to be trusted

In the final image, Li is shown sitting handcuffed before two policemen who tell her she has a "shallow understanding of secrecy for a state employee".

China's state secrets law is notoriously broad, covering everything from industry data to the exact birth dates of state leaders.

Information can also be labelled a state secret retroactively.

President Xi Jinping has overseen a sweeping revamp of the security apparatus, aimed at combating threats both at home and abroad.

But new security laws he has passed, or wants to pass, have alarmed Western governments, including the counterterrorism law and a draft cyber security law, amid a renewed crackdown on dissent.

It is not known if Huang Yu has already been executed

On Tuesday, a Chinese man was sentenced to death for leaking more than 150,000 classified documents to an unidentified foreign power.

The man, a computer technician from Sichuan named as Huang Yu, worked for a government department which handled state secrets, but he was a bad employee and was sacked, a report on state television said.

Filled with anger, he messaged a "foreign spy organisation" on the internet and offered to sell documents he had obtained while working for his former employer, who gladly took him up on his offer.

The report did not say when or if the execution had happened, or where he was tried.

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