SAN FRANCISCO (Reuters) - A man whose beating by two San Francisco-area sheriff's deputies was caught on videotape filed a federal lawsuit on Monday against the officers, claiming that after the assault officers stole his gold chain and took a "trophy" photo of him.

The lawsuit comes at a time of heightened scrutiny of police use of force as numerous high-profile killings of suspects across the country over the past two years have triggered waves of protest.

The lawsuit and authorities said Stanislav Petrov fled officers in what was believed to be a suspected stolen car on the night of Nov. 12, 2015. The complaint said the vehicle was an overdue rental.

After a high-speed chase across the Bay Bridge, Petrov got out of the car and fled from Alameda County Sheriff Deputies Paul Wieber and Luis Santamaria in a San Francisco alleyway when he was tackled to the ground.

A security camera video, which went viral after being uploaded to YouTube the day after the incident, shows the deputies punching and hitting Petrov with batons at least three dozen times as he screams "I'm sorry," "Help me" and "Oh my God."

Petrov tries to stand, then seems to surrender while shielding himself from the blows. Officials said Petrov suffered a concussion, multiple broken bones in both hands, a mild traumatic brain injury and deep lacerations to his head.

Prosecutors did not charge Petrov with any crimes related to the incident. The lawsuit said at least six other deputies witnessed the arrest, one of whom also struck Petrov.

"We intend to make sure that justice includes reforming the corrupt culture in the Sheriff's Office that allowed these crimes to happen in front of so many deputies," Petrov's attorney Michael Haddad said in a statement.

Representatives for the Sheriff's Office could not be immediately reached for comment.

The lawsuit alleges that after the assault, a third deputy stole a gold chain off of Petrov and bribed witnesses with the jewelry and some of Petrov's money to keep them from talking. Two deputies also took a "trophy photo" of a bloodied Petrov as he lay on the ground, the suit said.

In May, the San Francisco District Attorney's Office charged Santamaria and Wieber with assault under color of authority, assault with a deadly weapon, and battery with serious bodily injury over the arrest. Both pleaded not guilty.

(Reporting by Curtis Skinner in San Francisco; Editing by Andrew Hay)