Canned goods, batteries, bread and bottled water have vanished from store shelves and long lines of cars circle gas stations, as Japan grapples with a new risk set off by last week's earthquake, tsunami and ensuing nuclear crisis: panic-buying.

Far outside the disaster zone, stores are running out of necessities, raising government fears that hoarding may hurt the delivery of emergency food aid to those who really need it.

"The situation is hysterical," said Tomonao Matsuo, spokesman for instant noodle maker Nissin Foods, which donated a million items including its "Cup Noodles" for disaster relief. "People feel safer just by buying Cup Noodles."

The company is trying to boost production, despite earthquake damage that closed down its facilities in Ibaraki prefecture until March 15.

The frenzied buying is compounding supply problems from damaged and congested roads, stalled factories, reduced train service and other disruptions caused by the March 11 magnitude 9.0 earthquake off Japan's northeast coast and the major tsunami it generated, the Associated Press reported.