Jets which were spotted flying over Norwich were taking part in a pre-planned exercise, the US Air Force has confirmed.

A number of people reported seeing jets flying over the city early on Tuesday morning.

The US Air Force said the aircraft were in a 'holding pattern waiting clearance to land' at RAF Lakenheath.

A 48th Fighter Wing spokesperson added: 'As part of the pre-planned and publicised exercise taking place 1-3 Oct, the aircraft flying over Norwich this morning were in a holding pattern awaiting clearance to land.

'In our continued commitment to mitigate impacts for surrounding communities, we ensure to the maximum extent possible that this type of overland flying does not take place during established quiet hours, which end at 6am.'

It comes after the US Air Force warned people in Norfolk and Suffolk of increased night flights due to a 48-hour readiness exercise.

The force warned of aircraft taking off, landing and transiting between RAF Lakenheath and training ranges over the North Sea several times between sunset and sunrise from October 1 to October 3.

Col. William L. Marshall, 48th Fighter Wing commander, said: 'The Airmen assigned to RAF Lakenheath are prepared to fly in the defense of our nation, the United Kingdom and our shared allies 24 hours a day, seven days a week.

'We know the call could come day or night, and training like this helps us maintain our ability to respond under any conditions.'

Exercises like this provide both aircrew and support personnel stationed at RAF Lakenheath the experience needed to maintain a ready force capable of ensuring the collective defence of the NATO alliance.