TOKYO - A trading firm employee has been referred to prosecutors by Tokyo police for allegedly leaking a highly detailed three-dimensional map to a third party in China, possibly as part of an espionage operation, investigative sources said Thursday.

The 60-year-old resident of Saitama Prefecture, who is a former Chinese national and now a naturalized Japanese citizen, is suspected of buying the digital data from NTT Data Corp. by telling the information technology firm he would use it for his own marketing purposes, they said.

The Metropolitan Police Department's Public Security Bureau has been working on the case, searching some locations last year for leads about who the man has been in contact with, the sources said.

The police believe the map, bought for 2 million yen ($19,000) on a hard drive under a contract that prohibited its sale to a third party, may have been taken to China for military purposes, they said.

According to NTT Data, the highly accurate map was compiled using data from the Japan Aerospace Exploration Agency's satellite among other sources. The data, typically used for infrastructure development and disaster prevention purposes, is detailed enough to confirm the height and shape of buildings as well as topographical features.

He is also under suspicion for handing over other types of information to the Chinese, the sources said without elaborating.

==Kyodo