BEIJING — China has handed a ten-year prison term to an individual who leaked secret military documents and photographs to a foreign spy, state media reported on Monday, without naming the country involved.

China is working to strengthen its internet security after revelations that the U.S. government spied on a top Chinese telecommunications firm.

The individual, surnamed Li, was approached by a foreign intelligence agent via a popular social media platform, state media said.

Li leaked 13 highly classified documents, the official China Daily reported, which featured in the second highest tier in the country's three-tiered system for ranking military secrets. Li also leaked 10 classified secrets from the bottom tier.

Li had provided secret military journals and information about bases in the southern province of Guangdong, the report said.

But state media did not name the country benefited by the leaks.

China's military has warned that it faces a "severe and complex" task in maintaining secrecy, especially given the widespread use of the Internet and mobile communications, and needs to ensure tighter security.

Li was working in an unnamed coastal city, according to the website of the official People's Daily, when an Internet user claiming to be a woman got in touch on the Chinese instant messaging service QQ.

Over a month, they became friends, and the user, whom the paper called a "spy from outside China's borders," was revealed to be male.

The user adopted the moniker "Flying Brother," and paid Li to subscribe to secret military publications via China's National Library.

Li also leaked a large amount of information on the development of military bases and pictures of military gear, the People's Daily said.

"This presented a grave danger to the security of our country's military," it added.

"Flying Brother" sought out military hobbyists online and recruited 40 people throughout China to provide military information, the paper said.