A huge military plane able to transport tanks and even helicopters was spotted flying "lower than the hills".

The booming sound of the Royal Air Force's newest airlifter the Airbus A400m Atlas filled the valleys and coast across Sussex yesterday as the plane soared just metres above the ground.

The Argus: The plane's routeThe plane's route (Image: ADSBexchange)

It travelled along the coast as low as 120 metres above the ground before turning up the Ouse Valley at Newhaven towards Lewes.

One person who saw the plane said: "It swooped down so low and then it was lower than the hills, you could just see the tip of the tail."

But the RAF has reassured people that it was "conducting a routine training sortie" and the flight was nothing to worry about.

The propellor-driven plane is almost 50 metres long and replaces the ageing C-130 hercules fleet.

It left from RAF Brize Norton near Oxford at around 11.30am before heading north over Sheffield and Leeds. The plane - which can carry up to 116 paratroopers - then turned south, via Essex, and continued towards Hastings and Eastbourne.

The Argus: The plane turning over SeafordThe plane turning over Seaford (Image: Katie Fosberry)

The pilot followed the coast along the Seven Sisters at around 400ft, banking over Seaford to turn inland towards Lewes.

Another person posted on Facebook to share their shock after seeing the plane come directly towards them.

"It shocked me as I thought it was gonna crash, it was facing my way."

A spokesman for the RAF said: "We had an RAF A400M Atlas operating over East Sussex yesterday. 

"The callsign was COMET 454.  The aircraft took off and landed at RAF Brize Norton and was conducting a routine training sortie."