Japanese airport police have found 30 bullets in an American Airlines crew member's carry-on bag and said the flight attendant apparently carried them through security checks at US airports.
Police at Tokyo's Narita airport seized the bullets after finding them during a security check before the man boarded his duty flight back to the US on Saturday.
Airport police official Masatoshi Ito said on Wednesday that the crew member - identified only as a male US citizen in his 50s - told police that he forgot to leave the bullets before boarding his Tokyo-bound flight. Carrying bullets in hand luggage during flights is illegal under US law.
Police released the man on Saturday as he posed no danger of destroying evidence.
Police are still investigating how the bullets were undetected when he arrived at Narita.