TORONTO -- A flight from London to Dublin was delayed on Thursday after a climate change protester disrupted take-off by refusing to sit down.

The unidentified man held up the flight while announcing “we have two generations of human civilization left if we carry on doing what we’re doing.”

“I’m very sorry. I’m extremely sorry for the inconvenience,” the smartly dressed protester added in a video recorded by Irish passenger Warren Swalbe.

When asked to sit down by a flight attendant, the protester said he did not “wish to fly with you, but I don’t wish to get off.”

“Well you’ll be thrown off,” a frustrated passenger shouted in reply while a chorus of passengers vented their annoyance at the man who was dressed in a shirt and tie.

“Can you do us all a favour and remove him from the plane?” Swalbe asked the flight attendant.

“How long are you going to be?” another adds. “Sit down and make your protest,” a third added.

BBC Newsnight editor Nicholas Watt happened to be on the flight and tweeted about the incident as it unfolded.

He said the flight was on the runway, about to take off, when a “smartly dressed man in late middle age” stood up to “deliver (a) lecture on climate change up and down the aisle.”

The flight was forced to return to the gate, Watt wrote, to be met by police when the protester was escorted off the plane.

“The final irony of the climate protest on our flight,” Watt tweeted. “We cannot take off until we have taken on extra fuel... to replace the fuel used up during the protest, our pilot notes with humour.”

In the fourth day of Extinction Rebellion protests in London the BBC reported several people blocking the entrance to London City Airport as one man climbed on top of a plane and others glued themselves to the floor.