China has warned soldiers against using smartwatches, high-tech spectacles and other Internet-connected wearable gadgets, saying they could "endanger security" after a recruit was caught trying to take a photograph of troops.

"The use of watches that have internet access, location information, and telephone conversation functions should be considered a violation of secrecy regulations at army barracks," the People's Liberation Army (PLA) Daily said.

The newspaper, which is the official mouthpiece of China's military, also warned against smartphones and high-tech spectacles.

"When officers and men put on these type of spectacles, it is extremely possible that army positions can be tracked, endangering the security of military operations," the report added.

The warning issued at the weekend came after the military learnt of a recruit who attempted to take a photograph of soldiers with a smartwatch at his barracks in the eastern city of Nanjing.

The man came out in a "cold sweat" after he realised how many functions the watch had, the report said, adding that security personnel confiscated it and analysed the data.

The report did not say whether the watch -- a birthday present -- was a recently released Apple smartwatch, and did not specifically name Google Glass when referring to spectacles.

China operates a vast security and surveillance apparatus, with the ruling Communist Party maintaining a resolute grip on power, while Washington and Beijing frequently trade accusations of state-sponsored cyber-spying.

The foreign ministry in Beijing says China is a victim of hacking and has defended a new anti-terror law which demands US tech firms should hand over their encryption keys if they want to do business in China.

The measures, announced earlier this year, are purely internal and "a requirement for the Chinese government to prevent and combat terrorism", it said.