TOKYO, March 5 (Xinhua) -- A large metal object may have fallen off an airplane while flying close to Japan's Narita airport, authorities said Monday.

The one kilogram, trapezoid-shaped object, was spotted by a local resident on Sunday, according to Narita city government officials.

The white, metallic object, which was 25 centimeters in width and 50 cm in height, was found on a mountain roughly seven km away from the busy airport's B runway and just 30 meters from a residential area, the officials said.

Japan's transport ministry stipulates that airlines are to report any instances of lost or missing parts if they are 100 square-centimeters or larger.

The ministry also requires it is to be informed if the missing parts, in the case of them being non-metal, are reported if they weigh in excess of 200 grams.

For metal parts, if the weight is 100 grams or more, the missing part must be reported to the ministry.

Two similar instances in September last year caused local residents and passengers here concern.

The first being a panel falling off a KLM Royal Dutch Airlines plane and striking a car after the plane took off from Kansai International Airport.

The second incident involved an inbound All Nippon Airways aircraft arriving at Narita airport losing a panel twice in the same month.

The Narita city government and the transport ministry are currently trying to determine if the sizable object found on Sunday is part of an aircraft.