A Japanese defense attache at the Japanese Embassy in Beijing was effectively expelled by Chinese authorities on the grounds that he had entered an off-limits military area in the city of Ningbo, Zhejiang Province, Foreign Ministry and Defense Agency officials said Thursday.

The government had the attache returned to Japan on Wednesday after Beijing asked him to voluntarily leave the country, the officials said.

According to Defense Agency officials, Maritime Self-Defense Force Capt. Hiromasa Amano, 43, was detained by Chinese Navy officials in front of a military facility's gate in the city on Oct. 26 when he entered the area in a taxi.

Agency officials quoted Amano as saying he was not aware the area was off-limits.

He was confined to a hotel room for questioning by Chinese security officials for 13 hours until early the next morning, they said, adding that his notebook, voice recorder and data cards for his camera and video camera were confiscated by Chinese authorities.

Amano was on a six-day inspection tour in the city, which is home to the command post of the Chinese Navy's East Sea Fleet, the officials said.

Japanese Ambassador to China Koreshige Anami lodged a protest against the Chinese Foreign Ministry on Nov. 1 that the long detention of a foreign attache violates the Vienna Convention, the officials said. However, the government had Amano returned voluntarily because it would no longer be possible for him to continue his duties as attache in the country, they said.

According to the agency, Amano is the third Japanese defense attache to be expelled. Similar cases occurred in China in 1996 and in Russia in 1987.

Capt. Amano was sent to Beijing in April 2000 as the first attache in China from the MSDF. Japan still has two other defense attaches from the ground and air forces stationed in Beijing.