Toyota Motor Corp. reportedly is talking with joint-venture partner General Motors Corp. about building its Prius hybrid-electric vehicle at their California joint venture plant.

It’s not the first time New United Motor Mfg. Inc. in Fremont has been sited as a possible U.S. production site for the Prius.

In late 2004, California Gov. Arnold Schwarzenegger traveled to Japan to meet with then-Toyota President Fujio Cho to pitch NUMMI as good location for Prius production.

Japanese business newspaper Tokyo Shimbun says Toyota will ship major Prius components from Japan to California if it decides to build the top-selling HEV in the U.S. at NUMMI.

Producing more Prius cars, which have seen U.S. demand rise 22.6% through April in light of high gas prices, consistently has been a goal for the No.1 Japanese auto maker.

In a conference call with media early this month, Toyota Motor Sales U.S.A. Inc.’s Bob Carter, group vice president and general manager-Toyota Div., said the auto maker had a scant 3.5-day supply of the Prius.

Over the years, Toyota has been able to wring more units out of its Japanese plants but typically likes to build where it sells. The U.S. is the leading market for the midsize HEV hatchback, which year-to-date is the ninth best-selling passenger car in the U.S., according to Ward’s data, with 64,664 units delivered.

Toyota in a statement today denies it has made any decision on building the Prius at NUMMI.

NUMMI builds Toyota’s Corolla compact car and Tacoma compact pickup truck, as well as GM’s Pontiac Vibe compact hatchback.