A large bang heard by hundreds of people across the country was caused by two Typhoon aircraft responding to an emergency, the Ministry of Defence has said.

The RAF jets were responding to a small civilian helicopter that had emitted an emergency signal on a frequency it should not have been using, but the error was realised too late.

An MoD spokesman said the fighter planes had been authorised to go supersonic and were already on their way to the helicopter.

He said: "We can confirm that a small civilian aircraft was transmitting inadvertently on an emergency frequency at approximately 1810.

"Two typhoons from the Quick Reaction Alert (QRA) responded accordingly and authorisation was given from them to go supersonic, which resulted in the sonic boom. There was no actual threat to the civilian aircraft and they soon rectified their mistake."

A sonic boom is the sound associated with the shockwaves created when an object travels through the air and breaks the sound barrier. The noise contains large amounts of sound energy, meaning sonic booms are often mistaken for explosions.

Reports of Thursday night's sonic boom came in from Bath, Swindon, Coventry, Rugby and Oxford. Speculation about what could have caused the noise ranged from a large explosion to an underground tremor.

It is the second time this year that a sonic boom has been created by a Typhoon aircraft. In January, the MoD confirmed that a loud noise heard by people across the North of England was caused by an RAF fighter jet breaking the sound barrier.

Dan Cross, bar and restaurant supervisor at Millsy's in Earlsdon, Coventry, said the noise was so forceful it shook the walls of the restaurant.

"It sounded like it was coming from the kitchen," he said. "I thought somebody had dropped one of the big ovens in there. It was a really loud bang and the room shook and all the wine glasses on the rack shook. When it wasn't coming from the kitchen I thought maybe it was the cellar, but then wondered if it could be something else. It was weird, but didn't last long."

The Typhoon is a Bournemouth Air Festival favourite - and while we can't show you what the sonic boom sounds like you can download the sound of her in flight here...