A disabled Singaporean man has been arrested and indicted after allegedly arriving at Narita International Airport with about 4 kg of stimulants concealed in a seat cushion for his wheelchair, according to investigative sources.

The suspect, 47, has denied any knowledge of the stimulants, the sources said Monday, adding the arrest was made Sept. 5. They said the man has already been indicted by the Chiba District Public Prosecutor's Office on charges of violating the stimulant drug control law and the customs law.

Customs authorities estimate the stimulants, packed in four small bags, have a street value of ¥360 million.

A customs source said the case "is quite unconscionable because he probably tried to take advantage of inspectors' attitude toward the disabled," thinking they wouldn't make a thorough search.

The suspect arrived Sept. 5 via Taipei from Hong Kong, flying on Cathay Pacific Airways.

Authorities made a record 68 discoveries of illegal stimulants last year at Narita.