In a shocking video a man is shown hurling racial insults and death threats at an Iranian couple travelling on the subway in New York.

Mahsa Mehrdad and her boyfriend Masih Rahmati from Iran were subjected to a torrent of abuse by a fellow passenger while taking the Subway uptown.

Mehrdad filmed the last minute of the distressing exchange which shows the man telling her and Rahmati to "go back to your own country" and threatening "to put a bullet in their heads", because they were "terrorists".

He also repeatedly shouted "Donald Trump, Donald Trump is in your house!"

She shared the video on Facebook. It has been viewed more than 20,500 times.

"We noticed him getting on the train at 42nd St because he was looking at us hatefully and grumbling something under his breath. When the train got less crowded at 59th St, he started cursing loudly the whole way till 125th St," Mehrdad wrote in a Facebook post accompanying the video.

She added that they both tried to stay calm and ignore the man, even though they found the experience incredibly "sad and shocking."

Mehrdad also added that the incident made her wonder how one should act in such a situation. "Should we remain silent or should we do something? What is a proper action to shut down racist comments while not escalating the situation?" she asked.