Toyota Motor Corp. and its Silicon Valley partner, Tesla Motors Inc., will develop an electric version of Toyota's RAV4 SUV, reported The Detroit News.

The two companies will work on prototypes combining the popular RAV4 with a Tesla electric powertrain. They expect to sell the SUVs in the United States in 2012, the two companies said.

A first prototype already has been produced.

"Tesla's goal is to produce increasingly affordable electric cars for mainstream buyers -- relentlessly driving down the cost of EVs," the Palo Alto-based firm said in a statement.

Tesla now sells an electric roadster priced at just over $100,000, while Toyota is a leader in gas-electric hybrid vehicles. It has said it was planning to start selling electric cars in the United States in 2012.

The two companies announced in May that they would team up to develop electric cars.

Toyota invested $50 million in Tesla, in a side deal to the firm's initial public offering. Tesla bought a factory in Fremont, near San Francisco, where Toyota and General Motors Co. had produced vehicles in the joint North American Motor Manufacturing Inc. venture for 25 years until its closure this year.

Tesla did not say where the electric RAV4 SUVs will be assembled, but the prototypes are being built at its facilities.