The American Civil Liberties Union (ACLU) has released unsettling video footage that it says shows a Minnesota police officer exhibiting a "textbook case of excessive force" during a 2016 arrest.

The video features Agent Joe Joswiak of the Buffalo Ridge Drug Task Force repeatedly punching, elbowing and kicking Anthony Promvongsa, a 22-year-old Asian male, after pulling him over on 28 July.

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The clip was captured by the dashcam of Joswiak 's police vehicle. It shows him ordering Promvongsa out of his car only to open the door and begin attacking him within a few seconds of the demand.

The law enforcer seen assisting him with the arrest, Worthington Police Sergeant Tim Gaul, has been named in two other excessive force cases, according to NBC.

"Without hesitation, Agent Joswiak pulled, punched, and elbowed Anthony several times in the back while Anthony was still restrained by his seat belt," a statement from the ACLU Minnesota branch read.

"Agent Joswiak then yanked Anthony out of the car, threw him to the ground, and pressed his knee to the back of Anthony's neck to pin Anthony facedown on the pavement while he and Sgt. Tim Gaul of the Worthington Police Department applied handcuffs," it added.

The ACLU is now calling for an investigation into the incident, arguing that the lack of action from the relevant authorities amounts to condoning Joswiak's behaviour.

However, Buffalo Ridge Drug Task Force and Worthington Police Department said, in a joint statement, that the video shows only a "short segment" of the day's events and warned against viewing it in a "vacuum".

They added that Promvongsa had been charged with two counts of assault using a dangerous weapon (a car), one count of fleeing an officer in a motor vehicle and possession of a small amount of marijuana.

The ACLU said: "The video we have of Agent Joswiak and Sgt. Gaul seems to reveal at least two police officers who believe that they are above the law, not bound by it."

Last week (16 June), Minnesota police officer Jeronimo Yanez was cleared of murder in relation to to the November 2016 death of 32-year-old black man Philando Castile.

The aftermath of the shooting was streamed on Facebook live by Castile's girlfriend Diamond Reynolds.