Heathrow Airport said it is dealing with a "serious accident involving two vehicles" on the airfield after several passengers reported on Twitter that they had suffered delays on the tarmac and at their gates.

In a post to Twitter the airport said the incident involved "two members of staff", adding: "An investigation is underway and we are working with the police. This incident didn't involve any passengers and is not expected to cause any impact on journeys today."

Despite the airport insisting the incident would not impact journeys, a number of passengers posted to Twitter that they had suffered problems.

Alastair MacLeod tweeted: "Apparently there has been an accident on one of the runways at @HeathrowAirport and many planes (including this one) are parked on the apron with unspecified delays of 'hours'.

"No public news of this and no useful updates from @British_Airways - anyone out there know any more?"

After Heathrow responded to say the accident was not expected to impact journeys, Steven Ross replied: "With respect, it is impacting journeys departing B gates - BA710 to Zurich delayed by +2 hrs and aircraft change required. Sending good wishes to injured staff."