The director of the Jiangsu National Security Education museum in Nanjing, who would only give her name as Ms Qian, said the collection of tiny pistols, miniature cameras, and concealed wiretaps may be timeworn, but is still too sensitive for foreign eyes.

"We don't want such sensitive spy information to be exposed to foreigners, so they are not allowed to enter," she said.

"We have a range of documents and gadgets dating from 1927, when the Communist Party's Central Committee espionage department was founded, to the 1980s.

"We were ordered by the National Security bureau of Jiangsu province not to let foreigners see it."

No photography is allowed inside the museum either, she said...