TOKYO (AFP) - "Japanese authorities have found the body of a man in the landing gear of a Delta airliner that arrived in Tokyo from New York and said Monday they were seeking US help in identifying him.

The man, who was of dark complexion and dressed only in blue jeans and a long-sleeved shirt, was carrying no passport or personal belongings.

A mechanic found the body in the landing gear bay of the Boeing 777 after Delta Flight 59 landed at Tokyo's Narita International Airport at about 6:05 pm local time Sunday, a Chiba prefecture police spokesman said.

"Doctors say he probably froze to death and that he suffered a shortage of oxygen at an altitude of more than 10,000 metres (about 30,000 feet)," said another police official, Narita airport station spokesman Yoshimi Ichihara.

"We found no passport, no bag and no personal belongings. If he carried any luggage, it must have all dropped out when the airplane opened up the hatch of the landing gear bay above the ocean before it landed."

Japan was seeking help from US police to identify him, he said.