Sparked by fears of burned buttocks, Japan's leading toilet maker is offering to repair 180,000 bidet toilets for free after wiring glitches caused several to catch fire, the company said Monday.

The electric bidet accessory of Toto Ltd.'s Z series caught fire in three separate incidents between March 2006 and March 2007, according to company spokeswoman Emi Tanaka. He said the bidet sent up smoke in 26 other incidents.

"Fortunately, nobody was using the toilets when the fire broke out and there were no injuries," Tanaka said. "The fire would have been just under your buttocks."

The company will repair 180,000 toilet units manufactured between May 1996 and December 2001 for free, she said. A manufacturing defect is thought to have led to the faulty wiring.

Toto has been a pioneer in high-tech toilets fitted with pressurized water sprayers -- a standard fixture in Japanese homes.

The popular Z series offers a pulsating massage spray, a power dryer, built-in-the-bowl deodorizing filter, the "Tornado Wash" flush and a lid that opens and closes automatically. Prices range from 1,680 U.S. dollars to 2,600 dollars.

The model is not sold outside of Japan.