Japan is questioning a naval petty officer who is alleged to have obtained confidential data on the US-developed high-tech Aegis combat system without authorisation, the defence ministry said last Wednesday.

The 33-year-old petty officer second class, whose name has been withheld and who is married to a Chinese woman of the same age, has denied having passed the data outside of the Japanese naval force, press reports said.

Japanese police and and the naval internal investigative unit are cooperating in the probe, the defence ministry's press office said, declining to provide specific details.

They are trying to determine how the secret data ended up in the possession of a rank-and-file officer, the Jiji and Kyodo news agencies said.

The Aegis system has a cutting-edge radar and can launch missiles at more than 10 targets at one time. The Japanese naval force has five Aegis-equipped vessels.

The petty officer could have violated a domestic law which protects secrets involving US forces stationed here under an alliance, the reports said. If convicted, he could be imprisoned for up to 10 years.

The case has unfolded since the officer's wife was arrested in late January for a visa violation, reportedly agitating the US Department of Defense.

Police found and confiscated at the couple's home hard disks containing data on the Aegis radar and missile system and Aegis-equipped destroyers, the reports said.

The petty officer, a crew member of a destroyer, belongs to an escort flotilla based in Yokosuka at the mouth of Tokyo Bay.

He was a crew member in charge of the machinery part of the Aegis destroyer Kirishima from 1995 to 1999. He was not authorised to access Aegis data at that time.

He has told the police he obtained the data from a crew member of another naval ship, the reports said.

Source: Agence France-Presse