CHICAGO (Reuters) - A Chicago police officer has been relieved of his duties after a video posted online showed him stomping on a man's head during an attempted arrest, officials said on Tuesday.

The officer will be relieved of duties while the Independent Police Review Authority investigates the incident, police spokesman Anthony Guglielmi said in an emailed statement to Reuters.

The police department identified the two officers as white males, and the man being arrested as black, without giving names. The department did not say why the two officers were struggling with the man, but charges are pending against him.

"After careful consideration and reviewing the video footage, Superintendent (Eddie) Johnson has decided to relieve one of the officers involved in the incident," Guglielmi said.

The incident comes as the third-biggest U.S. city's police department grapples with a strained relationship between officers and minority communities and amid a federal probe launched after the release last fall of a video showing a white police officer fatally shooting a black teenager.

The latest video was posted by a bystander on Facebook on Monday afternoon soon after the incident, according to the Chicago Tribune.

The video, which was later posted by several media outlets, showed a plainclothes police officer on top of a man, struggling to arrest him. A second police officer arrived on the scene on the city's West Side and began to direct bystanders away from the altercation. Moments later, the second police officer stomped on the man's head and he appeared to lose consciousness.

Mia Sissac, a spokeswoman for IPRA, confirmed the police watchdog agency was investigating the incident, but declined to provide further details.

(Reporting by Justin Madden; Editing by Dan Grebler)