Police have confirmed a passenger was removed from the flight on Wednesday evening following a “verbal altercation”.
The DUP has declined to comment on the incident but a party source has confirmed Sir Jeffrey was the other passenger involved.
The source said a man had been verbally abusive towards the DUP leader.
A spokesperson for the Metropolitan Police said: “At around 5.30pm on Wednesday, March 20, airline staff at Heathrow Airport made police aware of a verbal altercation involving two male passengers during boarding.
“One man was removed from the flight.
“There were no arrests.”
Earlier this year, Sir Jeffrey told the Commons how he had been subjected to threats as he continued his negotiations with the UK Government over a deal on post-Brexit trading arrangements.
The DUP later confirmed the matter had been reported to the police.
An investigation into the alleged threats against Sir Jeffrey detected no criminal offences, the PSNI said.
