A plane was forced into an emergency landing after a passenger screamed he would kill everyone on board unless they "accept Jesus was a black man".

The disturbing incident, just 20 minutes into a flight from Seattle to Chicago on Saturday evening, resulted in the unnamed man being subdued and later arrested.

An Alaska Airlines spokesperson said the offender, who was later held on suspicion of harassment, became "extremely belligerent and physically aggressive during the ascent".

It took flight crew and multiple passengers - including a police officer who happened to be on board - to restrain him, while the plane flew back to Seattle-Tacoma Airport.

The suspect is seen moving through the cabin as he makes the threats

On landing, Port of Seattle Police took the man to the King County Jail where he was being investigated on suspicion of harassment.

A video shows him shouting: "I will kill everybody on this plane unless you accept Jesus was a black man."

Wearing a T-shirt and face mask and with the plane still in ascent, he continues to move amongst shocked fellow passengers on Flight 422, repeating "accept it" and "die in the name of Jesus".

Other passengers and cabin crew then subdued him

In the footage, initially obtained by NBC's King 5 station, the suspect is followed through the aisle while the majority of passengers are buckled into their seats.

He is then seen being tackled to the ground with one man telling him to stay down and another assuring passengers everything is under control.

A flight attendant then announced over the loud speaker the plane had been forced into an emergency landing, adding "we have everything under control", according to reports.

The flight, which took off around 11.15pm and was headed for Chicago O'Hare, was subsequently cancelled and passengers were booked on a different flight.

One passenger told KOMO News that the passengers who helped subdue the suspect should be considered heroes.