A Chinese snack bar owner has been jailed for 10 years for disclosing military secrets including documents and photographs of equipment to "foreign intelligence agencies", state media said Monday.

The suspect, who was surnamed Li and from the southern province of Guangdong, was approached online by "a foreign spy" with the username "Feige" -- "flying brother" in Chinese -- the official Xinhua news agency reported.

"Since 2007 Feige has lured 12 people in Guangdong and 40 others in more than 20 provincial regions to provide military information through online bookstores and military enthusiast websites," the Xinhua dispatch said.

The report did not detail which country Feige worked for, but said Li passed information to "foreign intelligence agencies".

It cited a source at "national security agencies" in Guangdong.

Li, 41, from Shantou, disclosed 23 classified documents and also monitored military bases, passing on photographs of military equipment, it said, adding he also subscribed to "internal military publications" for Feige.

There was no indication how Li obtained the papers. Xinhua did not specify any court that convicted and sentenced him.

Asked which countries were involved, foreign ministry spokeswoman Hua Chunying said she did not know about the case and it was outside the ministry's remit.

Beijing announced a double-digit rise in its defence budget in March and has rapidly expanded its military in recent years, rattling its neighbours and attracting the attention of the US, which is making a foreign policy "pivot" towards Asia.

President Xi Jinping has made security concerns a top issue, and chaired the first meeting of the country's new national security commission three weeks ago.