A former police informant, who had a £40,000 contract put on his head after a successful undercover drugs operation, has launched a damages action against the chief constables of three North-East police forces for allegedly failing to protect him.

Pilot Terence Donnelly, 60, who is believed to be seeking in excess of £100,000, remained hidden behind a large green screen at the High Court in London as his case was presented to trial judge, Mr Justice Leveson.

His claim arises out of the assistance he gave between 1994 and 1997 to the then Regional Crime Squad (North Eastern Region) as a "participating informant", including flying an aircraft from Holland to the UK carrying up to £6.8m worth of drugs, which led to the arrests of those involved.

Mr Donnelly, who has had to leave his Lincoln home to live at an undisclosed address, is suing the chief constables of the ten forces which made up that squad - Lincolnshire, Derbyshire, West, North and South Yorkshire, Humberside, Cleveland, Durham, Northumbria and Nottinghamshire - and two police officers.

He claims the police failed to protect him and his identity. He says he should have been given a new identity and also claims he was promised a job abroad.

The defendants are contesting the case, which is expected to last until early next week. The judge is being asked to decide the issue of liability at this stage and not the amount of damages, if any, to be awarded.

Mr Donnelly, who wishes to start a new life abroad, argues that he should have been given protected witness or informant status, and that the police were negligent in not doing so.

His counsel, Richard Jones QC, told the judge that, in 1994, Mr Donnelly was living in Lincoln when he was approached by an individual who asked if he would be interested in "bringing in gear" - drugs - into the UK.

He also saw a group of schoolchildren he believed were under the influence of drugs and reported the matter to police, which led to him being introduced to a detective constable in the regional crime squad.

Mr Jones said Mr Donnelly flew into the UK from Holland in an operation codenamed Operation Buzzard, with a consignment of about 50kg of amphetamine sulphate, in August 1995.

Key facts that did not appear to be in dispute, said counsel, included that Mr Donnelly "undertook very substantial personal risks" in assisting the police, including meeting key individuals involved in importing Class A drugs into the UK when wearing recording and radio transmitting devices.

The case continues.