TOKYO, August 10, 2008 (AFP) - A South Korean resident in Japan was arrested on Sunday over a bomb threat to Air China's Tokyo office last week after the man turned himself in earlier in the day, police said.

Lee Hyon-Sa, a 33-year-old South Korean national, went to a police station in Kanagawa prefecture, west of Tokyo, according to a Tokyo police spokesman.

Lee claimed responsibility for the crime and was arrested on charges of forcible obstruction of business, he said.

The Tokyo office of Air China received a threat Friday to bomb its aircraft and crash planes into the site of the Beijing Olympics, just hours before the opening ceremony.

The threat forced one of its planes bound for China to turn around and return to Japan, although inspections of the aircraft and four other Air China jets found no suspicious objects, according to Japanese authorities.

A Narita airport police officer said the threat sent was: 'We are telling Air China: Immediately suspend operations of all flights. Otherwise we will bomb the planes. We will crash the airplanes into the site of the Olympics.'

The threat came as China enforced sweeping security measures across Beijing to protect the Olympic opening ceremony, deploying thousands of armed police and locking down areas of the city centre.