"The fire occurred as a result of an electrical failure in the charging system for an electric vehicle," said a report by the fire authority, a copy of which was obtained by Reuters.

While Tesla Motors Inc maintains that the fire was not related to the car or its charging system, the Orange County Fire Authority said the Tesla-supplied charging system or the connection at the electricity panel on the wall of the garage of a single-family home could have caused the fire.

A fire department in Southern California said a garage fire may have been caused by an overheated charging system in a Tesla Model S sedan, in the latest link between the top selling electric car and the potential for fire.

The report also emphasizes that the cause of the fire is unclear.

"The most probable cause of this fire is a high resistance connection at the wall socket or the Universal Mobile Connector from the Tesla charging system" which was plugged into a 240-volt wall socket, the report said.

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The fire occurred on November 15 in Irvine, California. The possible link between the fire and the Tesla Model S was not reported previously.

The garage fire is not related to three road fires in Model S sedans that occurred in October and November and which caused Tesla's stock to fall sharply last month. The road fires occurred in Washington state, Tennessee and Mexico.

In the U.S. incidents, Model S sedans caught fire after running over road debris. In Mexico, a Model S caught fire after striking a concrete wall.

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U.S. regulators are investigating the cause of the U.S. road fires, which caused the high-flying stock of the "green" car maker to fall from a high of $194.50 in late September to under $120 in late November.

On Wednesday, Tesla shares fell 2.9 percent to close at $147.98 on the Nasdaq.

The November residential fire on the campus of the University of California-Irvine caused $25,000 of damage to the garage and its contents, but the Model S sustained only smoke damage, and no one in the house was injured, according to the Orange County Fire Authority's report.

A Tesla representative disagreed on Wednesday with some of the report's findings. "We looked into the incident," said Tesla spokeswoman Liz Jarvis-Shean. "We can say it absolutely was not the car, the battery or the charging electronics."

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She added: "The cable was fine on the vehicle side. All the damage was on the wall side.

"A review of the car's logs showed that the battery had been charging normally, and there were no fluctuations in temperature or malfunctions within the battery or the charge electronics," said Jarvis-Shean.

The owner of the Model S, who lives at the Irvine residence, had parked the car in the garage the evening of November 14, plugged the cord from the vehicle into the 240-volt wall socket, and set a timer to begin the flow of electricity to the car's on-board batteries at midnight.

She noticed a fire just before 3 a.m. and called for help. Fire crews put out the blaze quickly.

Some cardboard boxes stacked near the point of connection between the Tesla Model S charging system and the connection to the 240-volt outlet helped the fire spread, the report said.