BEIJING - China's chief intelligence agency posted on social media a comic strip featuring foreign-looking characters secretly extracting rare earths, in a story portraying the country's strategic metals under threat from covetous "overseas organisations".

The comic strip, published on Sunday on the State Security Ministry's official WeChat account, showed security officers uncovering "suspicious" exploration and mapping activities by a group of people supposedly doing survey work for real estate development.

No foreign government or agencies were named in the comic strip, and the ministry did not specify any measures to counter foreign "interest" in China's rare earths.

The ministry could not be reached for further comment.

China, the world's largest producer of rare earths accounting for nearly 90% of global refined output, last year introduced restrictions on exports of the elements germanium and gallium, used widely in the chip-making sector, citing the need to protect national security and interests.

It also banned the export of technology to make rare earth magnets, in addition to a ban on technology to extract and separate rare earths.

The restrictions have fanned fears that the supply of rare earths might ignite tensions with the West, particularly the United States, which accuses China of using economic coercion to influence other countries. Beijing denies the claim.

The United States has previously imposed restrictions on China's access to advanced chips and chip-making tools that could fuel breakthroughs in artificial intelligence and sophisticated computers for its military.

Rare earths, used widely in lasers, military equipment and consumer electronics, have grown in demand along with the rapid development of new energy vehicles, wind power and inverter air conditioners.

"As technology grows in leaps and bounds, some primary minerals have become rare strategic resources," a police character in the comic said.

"China boasts rich resources of these minerals. Overseas organisations have already had their eyes on them."

Set in fictional Xishan Mining Area - described as an area rich in critical and scarce mineral deposits that could bring breakthroughs in super-semiconductor technology - the comic depicts two officers that were sent to the area undercover as lost hikers to gather information.

State-controlled Global Times described the comic as underscoring the importance of safeguarding key mineral resources as China-U.S. trade frictions and global geopolitical tensions have turned the global competition for rare earths into an issue of national security.

The newspaper said the United States, Japan and the European Union, among others, have for a long time "coveted China's rare earth mineral resources".

"They have even resorted to infiltration, bribery, and espionage to achieve their goals," Global Times said, quoting Li Baiyang, an associate professor of intelligence studies at Nanjing University.