Dozens of flights bound for Heathrow were diverted or delayed this morning after an RAF plane demanded an ‘unplanned’ use of airspace.

At least four Heathrow-bound British Airways flights and one Virgin Atlantic aircraft were forced to land at other airports such as Gatwick, Stansted and Luton.

Meanwhile, many other flights were delayed as a result of planes being ‘stacked’ above Greater London as they waited for airspace to clear.

The closure of airspace – which began at around 9am on Friday – lasted for approximately 20 minutes.

Passengers aboard some of the affected flights revealed how pilots had informed them over the tannoy that the situation had been caused by a security incident.

However a Heathrow spokesman told MailOnline that the incident was not security related, but refused to elaborate further.

He added: ‘Arrivals were paused briefly this morning due to an RAF request for an operational flight within part of Heathrow’s airspace.

‘Arrivals are now operating as normal.’

A Ministry of Defence spokesperson added: ‘The RAF can confirm that a flight was completed this morning by one of our assets from RAF Northolt,

‘This flight was coordinated with Heathrow ATC but had to extend by a few minutes to complete its sortie. The minor delays caused to civilian air traffic are regretted.’

Passengers took to social media in the aftermath of the incident as they appealed for more information.

One wrote: ‘I’m on one of the few planes that were now cleared for landing’

‘Our pilot just informed us that they’re restricting arrivals to allow a plane with a security incident on board to land.’

Another passenger added: ‘Captain said Heathrow is closed for arrivals for a ‘security incident’ but nothing in the news. What’s going on?’

A third said: ‘Still on the ground and waiting for info.. Seems like there is two options right now, refuel and get back to Heathrow or bus to London.’