Speculation is escalating via Twitter that a major incident is taking place above the skies of the UK.The Flightradar24.com website shows Delta Airline Flight 99, en route from Paris to Detroit, circling in clear air over East Anglia for around the last hour. It is being kept clear of flight paths and other air traffic, and is circling continuously.Twitter users who have been monitoring the Flightradar website have speculated that a major terrorist incident may be underway, with some claiming that the transatlantic flight is under escort from French fighter jets.No official confirmation has been issued. The Drum has contacted Delta Airlines and awaits a response.The airline's live flightboard states the flight is currently "diverted" and "delayed".The UK’s standby airport for terrorist and other incidents is Stansted airport, only a few miles from the apparent site of the aircraft’s circular track.

A screengrab of the flight from a few moments ago

Twitter is going crazy about Delta flight #DAL99, should be on it's way to Detroit but circling over Norwich (UK) - http://t.co/eVF22oUN88 August 7, 2013

Flight DL99 from Paris to Detroit immediately changed course towards London. http://t.co/DT1c2t1L5c Live updates: http://t.co/712BoFh7S3 — Peter Sonneveld (@petersonneveld) August 7, 2013

#DAL99 with 2 French militairy jets next to it? Possible hijacking? @KLM@Schiphol" — Freedom of Info 4ALL (@ntisec) August 7, 2013

Delta Flight DAL99 Paris-Detroit diverted “@worldwidenieuws: @KetyDC And might go to Amsterdam later: pic.twitter.com/0oaSJzOdGH” — Kety Shapazian (@KetyDC) August 7, 2013

Updated: the flight landed safely at Amsterdam Airport earlier this afternoon after being rerouted.