Drunken partying on a British Airlines flight to the Caribbean escalated to violence when a passenger smashed a wine bottle during an argument — then used the broken glass to stab a fellow flier in front of the other petrified travelers, horrifying video shows.

The British Airlines flight from London to St. Lucia turned into a bloody nightmare Monday when the unidentified passenger went to the galley, grabbed the bottle and smashed it during the argument, The Sun reported.

He then used the shattered bottle to stab the other passenger — to the horror of other passengers on the plane, video shows.

“It was a truly frightening experience for the crowded passengers. There was a lot of understandable upset,” a source told The Sun

“The row turned into pushing and shoving then things suddenly got really nasty. It was horrifying when the passenger broke the bottle then used the shards as a weapon,” the source added.

An unidentified passenger grabbed the bottle and smashed it during the argument.

At one point during the melee, the attacker flung the broken bottle into the ceiling, according to The Sun, which published gruesome images of blood spatters from the projectile and glass shards in the galley.

The cabin crew intervened and one heroic flight attendant stood between the attacker — who is seen in the clip wearing a dark hat, denim jacket and glasses as he waves the broken bottle, according to the outlet.

“Suddenly there was blood in the cabin. No one knew how gruesome it was going to get. Witnessing that in such a confined space, and not knowing if or how the bloodshed was going to end, was horrific,” the source told The Sun.

“Some very brave individuals separated the two men and got them back in their seats. It could have been so much worse,” the insider added.

The captain radioed Hewanorra International Airport to request first responders and police be ready to immediately arrest the suspect when the plane landed about an hour and 20 minutes later.

Meanwhile, passengers have slammed British Airways for providing the attacker with too much alcohol during the eight-hour, 40-minute flight, the Daily Mail reported.

They claimed that several men had been partying loudly, consuming copious amounts of booze, and harassing and grabbing several female passengers before the incident, according to the outlet.

Smashed glass seen in the back of the plane
The attacker used the broken bottle to stab a fellow flier during an argument.

Stabbing caught on video n British Airways flight
Passengers have slammed British Airways for providing the attacker with too much alcohol.

Passengers told the Daily Mail that the crew failed to intervene in the lead-up to the attack and ignored the rowdy behavior, during which the group reportedly blocked access to bathrooms.

“The main aggressor was behaving terribly in the lead-up to the incident, the BA staff were perhaps too intimidated to regain control but the atmosphere was clearly leading to some kind of incident,” a woman told the news outlet.

“A handful of men were lingering at the back of plane for hours, loudly partying with an endless supply of alcohol provided by the BA staff,” she reportedly said.

Bloody mark seen on wall of the plane
The cabin crew intervened to prevent the attack from escalating.

“They approached numerous women on the flight, myself and a fellow passenger were grabbed by the arm when we passed by and pulled back as they tried to engage us,” the woman told the Daily Mail.

She claimed that “staff saw this and did not intervene.”

Another woman said the assailant told her his parents had just died and “was touching my arm and generally making me feel very uncomfortable.

“Flight attendants poured fuel on a fire. They allowed a party atmosphere where people were not able to go to the flight attendants and ask for anything because about 10 men were all stood up at the back of the plane blocking the facilities and drinking heavily,” she told the outlet.

The woman said female passengers “started panicking and did not stop crying” for the remainder of the flight.

A St Lucia police spokesperson told the Daily Mail that the incident remains under investigation.

“We are looking into this with immediate effect. This is a very serious matter which occurred on a plane. This is very serious indeed,” the rep said.

The suspect has not been named and information about criminal charges was not immediately available.

Blurry image of the attacker wearing a black hat.
At one point during the melee, the attacker flung the bottle into the ceiling.

British Airways did not immediately respond to a request for comment from The Post.

The airline told The Sun: “We’re shocked that anyone would act in this way and are grateful to our highly trained cabin crew and the customers who supported them in handling this difficult incident.”

“We want to assure customers that this behavior will never be tolerated and we will always take the appropriate action,” it added.