UKIP candidate Nigel Farage was injured today when an election stunt in a light aircraft went crashing to ground.

Mr Farage was in a plane towing a banner bearing the slogan "Vote for your country - Vote UKIP" when it went down at an airfield in Northamptonshire.

There was speculation that the accident, in which Mr Farage suffered head injuries, was caused when the banner got tangled up in the plane.

The MEP, who is also standing in the General Election in Buckingham, was taken to hospital with non life-threatening injuries following the crash at Hinton-in-the-Hedges airfield, near Brackley.

The plane went down just after 8am, also injuring the pilot, who was airlifted to Walsgrave Hospital in Coventry.

Former Ukip leader Mr Farage was taken to Horton General Hospital in Banbury.

A party spokesman said: "We've had unconfirmed reports that either the banner got snagged up or there were cross-winds and it was an unfamiliar airfield to the pilot, who had to be cut out of the plane."

Mr Farage suffered "minor head injuries" but campaigners had been told to "carry on", he said.

The aircraft was believed to be a 1960s-style biplane which left the Winchester area of Hampshire early today and flew into Hinton.

The accident happened as it was taking off again from Hinton, the spokesman said.

The plane was due to fly over Buckinghamshire, Oxfordshire and Northamptonshire.

The crash is being investigated by the Air Accidents Investigation Branch, supported by Northamptonshire Police.

A police spokesman said: "Just after 8am a light aircraft came down at Hinton-in-the-Hedges Airfield near Brackley in Northamptonshire.

"Two people were on board the aircraft, pilot and passenger, and both suffered what are believed to be minor injuries."

A 40-year-old man, who was working at the airfield when the accident happened, said: "I was in the hangar and suddenly all these ambulances and fire engines went past.

"I saw the plane take off. All I know is that it was banner-towing for Ukip."

Richard Harrison, who owns the airfield, said it had been closed and air crash investigators were on their way to the scene.

He said he did not know what caused the crash or the make of the plane involved.

Chris Adams, Ukip parliamentary candidate for Aylesbury, said: "Nigel was unconscious but he can talk.

"He's been coming in and out of consciousness and is now being X-rayed."

He said he had spoken to an aviation expert who said the banner could not have got caught up in the tail fin.

The wreckage of the blue and red aircraft is lying upside down in a field with the cockpit crushed.

The plane's registration is G-BWDF and according to the Civil Aviation Authority the owner is Sky Banners in Walton-on-Thames, Surrey.

It is a PZL-104 Wilga 35A, a Polish fixed-wing landplane.

A Ukip spokesman said: "Just after 8am this morning, a light aircraft carrying Nigel Farage, the Ukip MEP and chief spokesman, crashed at Hinton-in-the-Hedges airstrip in Northamptonshire.

"At this time we understand that the pilot has been taken to hospital in Coventry.

"Mr Farage has been taken to Horton Hospital in Banbury for his injuries.

"Ukip is sure that everybody involved in today's General Election will join us in hoping and praying that the pilot recovers from his injuries as soon as possible."

A spokeswoman for Northamptonshire Fire and Rescue Service said crews attended the scene and released the two passengers from the aircraft.