By Jonathan Stempel

(Reuters) - A Pennsylvania jury has ordered Mitsubishi Motors to pay nearly $977 million in damages to a man who said he became a quadriplegic in a vehicle rollover because of an alleged defective seatbelt.

Jurors in the Philadelphia Court of Common Pleas on Monday awarded Francis Amagasu, 58, and his wife $176,551,384 in compensatory damages and $800 million in punitive damages, according to Kyle Farrar, one of the plaintiffs' lawyers.

Mitsubishi said it was disappointed with the verdict and intended to appeal.

Amagasu's injuries stemmed from a Nov. 11, 2017 accident in Buckingham Township, Pennsylvania when, while wearing his seatbelt, he lost control of his 1992 Mitsubishi 3000GT as he tried to avoid another vehicle.

The plaintiffs said the seatbelt's design was defective because it allowed the release of four inches of slack during a collision, causing Amagasu to strike his head on the car roof.

They also said Mitsubishi failed to perform rollover testing, and that its conduct was reckless.

Jurors began hearing evidence on Oct. 20. They deliberated briefly on Oct. 27 before returning their verdict.

In a statement, Mitsubishi Motors North America called the damages award "egregious," and said there were "significant legal and evidentiary issues" to be addressed in an appeal.

"Mitsubishi Motors vehicles are and have been among the safest on the road, having won multiple safety awards to attest to that fact," it added.

Farrar, a principal at Farrar & Ball, said he thought the verdict would be upheld, reflecting Amagasu's injuries. He also said the ratio of punitive damages to compensatory damages was in line with U.S. Supreme Court guidance.

"The evidence regarding the defective nature of this seatbelt was overwhelming, and not something that the average consumer would ever know about," Farrar added.

(Reporting by Jonathan Stempel in New York; Editing by Marguerita Choy)