A viral video showing a man racially abusing an elderly passenger on a Ryanair flight has prompted widespread outrage and an investigation by British police.
The video -- now viewed on Facebook more than four million times -- appears to show a white man in an altercation with a black woman over seating arrangements in their row.
Despite protests from another passenger that the woman was disabled, the man can be heard threatening to push her and and calling her an "ugly black bastard" in the three minute clip.
A cabin crew member and a passenger can be seen intervening in an apparent attempt to calm the man, whilst another can be heard pleading for staff to move the woman.
But the no-frills Irish airline has drawn criticism on social media for failing to eject the abusive passenger from the flight.
"He refused to sit next to the woman because she was black," wrote David Lawrence, the man who filmed the incident, in a caption to the video on Facebook.
"Ryanair are accountable for the protection of their customers and they FAILED!"
"The elderly lady was moved to another seat whilst the man was allowed to continue his journey with extra room and on board service," he added on Youtube.
Lawrence also said he has drawn personal criticism for choosing to record the situation rather than intervene.
"One of the passengers whilst I was filming basically said to me don't you think you're being a bit childish by filming this," he told BBC Breakfast.
"I had to make a difficult decision at that time because if I had stepped in I don't think you would have seen the footage that I captured."
Lawrence said the video was filmed on flight FR 9015 from Barcelona to London Stansted on Friday 19 October.
British police say they understand the incident took place whilst the plane was on the tarmac at Barcelona airport.
Essex Police, the force with jurisdiction over Stansted Airport, told AFP they were made aware of the incident on Sunday and are now working with Spanish officers on an investigation.
"Essex Police takes prejudice-based crime seriously and we want all incidents to be reported," a spokesman said in a statement.
"We are working closely with Ryanair and the Spanish authorities on the investigation."
Ryanair said in a statement: "We have reported this to the police in Essex and as this is now a police matter, we cannot comment further".
Asked about the incident at a daily press briefing on Monday, Prime Minister Theresa May's spokesman said: "When people are travelling and going about their public life, no-one should be subjected to intimidation or any form of abuse".