PORTLAND — A Westbrook man is suing a Portland police officer, claiming the officer used excessive force during his arrest for assault last year.

Jabril Mohamud, 27, is suing Officer Jonathan Roberts, seeking $10,000 in compensatory damages and $10,000 in punitive damages. Mohamud, a Maine State Prison inmate who is representing himself, filed the complaint in Cumberland County Superior Court in May. The case was moved to U.S. District Court on Monday.

In his complaint, Mohamud says he was on his stomach, with his hands in front of him, on a fire escape when Roberts ordered him to put his hands behind his back. Mohamud said he tried to explain that he’d have to sit up to get his hands fully behind his back, given the narrow landing and his own size. According to Department of Corrections records, Mohamud is 6 feet 2 inches tall and weighs 248 pounds.

According to Mohamud, Roberts kicked him, used pepper spray and pushed him down the stairs after he was handcuffed. Mohamud says he broke his fall with his shoulder and knees, and that his knees and feet hurt so badly that he could not stand without help. Mohamud also accuses Roberts of directing racial slurs at him.

“The officer denies the allegations in the complaint,” said Mark Dunlap, a lawyer hired by the city for the suit.

According to police records, officers were called to Wilmot Street on Jan. 7, 2011, for a reported assault.

A female friend of Mohamud told police that they had been sitting in her car when they got into an argument. Mohamud punched her repeatedly in the face, banged her head against a window and choked her, she said.

In his incident report, Roberts wrote that Mohamud refused several orders to put his hands behind his back. Roberts said that after using the pepper spray, he cuffed Mohamud’s right hand and sat on his back to keep his left hand pinned under him until other officers arrived. Roberts wrote that no other force was used.

Mohamud pleaded guilty to assault in March 2011 and was sentenced to a year in prison. He is serving that penalty concurrently with a two-year sentence for violating probation. The underlying conviction is for drug trafficking.