"I will only confirm that he, in effect, urinated in the plane," a spokeswoman for the Air France-KLM subsidiary said, confirming a report on Europe 1 radio, which interviewed a passenger who witnessed the incident.
According to the passenger, who was not named, the 62-year-old was visibly inebriated and tried to stand up before take-off, when passengers are asked to wear seatbelts, declaring: "I want to piss, I want to piss."
When a stewardess asked him to wait 15 minutes until after take off when the toilets were to be opened, he said he could not. "And there and then he stood up and did it on the floor," the witness told the French broadcaster.
"We could see he had been drinking. The stewardess was dumbfounded," she added. "No one said anything. It all happened with courtesy. Mr Depardieu sat back down and the plane returned to the parking area to be cleaned."
The spokeswoman said the incident had taken place on Tuesday evening on board flight AF5010. She did not say whether the company intended to take further action against the popular French star.
A second company spokeswoman, who would not confirm Depardieu's identity for reasons of privacy, told AFP a "passenger" had been escorted from the jet at Charles de Gaulle airport following an "incident" before take-off.
"The flight was taxiing on the runway. The passenger refused to remain in his seat. It was the captain's decision it was best to return the plane to the stand," she said, adding the flight was delayed for one hour and 15 minutes.
The second spokeswoman said the passenger did not appear to the crew to be drunk and that he had offered no resistance. Police were initially called, but he was escorted from the plane by ground crew without trouble.
Depardieu was himself not immediately available for comment and his agent did not wish to make any statement on the events.
According to a Paris Airports website, the Dublin route is served by an Avro RJ-85, a regional jet that can carry up to 111 passengers and is routinely equipped with onboard toilets both fore and aft.
Depardieu is perhaps the best known face in French cinema, having appeared in almost 200 films, and is best known abroad as the star of the 1990 literary epic Cyrano de Bergerac and the US romantic comedy Green Card.
He is also a winemaker and in 1990 was convicted of drunk driving.