The Nikkan Kogyo said Toyota decided to take more time to ensure quality after it decided to forgo replacing the nickel-metal hydride battery used in the hybrid system with a lithium-ion battery for the first version of the new model.

Toyota and battery partner Matsushita Electric Industrial Co. are developing a lithium-ion battery that many expected would power the motor in the next Prius. The paper had said last month that those plans were also delayed due to safety concerns.

A Toyota spokesman declined to confirm the delay of the Prius launch, saying it was not possible to move back a plan whose timing had not been set.

"Our policy is to roll out any model when all the conditions are in place," he said.

The first Prius debuted in 1997 as the world's first mass-market hybrid car, and was vastly improved for the second generation launched in late 2003.

By far the best-selling hybrid car on the road today, the Prius has almost single-handedly boosted Toyota's image as a "green" carmaker, also helping drive sales of other cars.

Toyota is boosting production of the Prius by 40 percent this year to 280,000 units, although margins on the car are believed to be thin due to the high cost of the hybrid system.