But the court in Strasbourg said it was only the way the recordings were obtained which breached the human rights of James Hewitson, a 55-year old garage owner from Dorset, and not the recording itself.

Mr Hewitson was given a five-year prison sentence in 1997 for importing and supplying cannabis.

He failed to prevent tapes of his private conversations being used as evidence at his trial.

The prosecution acknowledged at the time that without the tapes it lacked sufficient evidence for a conviction.

Everyone has the right to respect for his private life. There shall be no interference by a public authority with the exercise of this right except such as is in accordance with the law and is necessary...for the prevention of disorder or crime. Article 8 of the European Human Rights Convention

At the start of his trial Mr Hewitson objected to the tapes, arguing that the authority for placing listening devices did not comply with Home Office guidelines at the time and the recorded evidence should be excluded.

But his claim was thrown out and, after the tapes were submitted as evidence, he pleaded guilty and was jailed.

The European Court of Human Rights pointed out on Tuesday that Home Office guidelines of 1984 said only chief constables or assistant chief constables could authorise the use of listening devices.

Even then authorisation was only granted if the crime was serious, if other investigation methods had failed, and if it was likely that recordings would lead to a conviction.

'No statutory system'

The degree of intrusion into the private lives of those affected by the surveillance also had to be justified by the seriousness of the alleged offence.

But none of that amounted to a "statutory system" to regulate the use of covert recording devices, said the human rights judges.

In fact, authorisation for such surveillance on a statutory basis only applied when the 1997 Police Act became law in 1998 - after Mr Hewitson's case.

Tuesday's judgment said the UK government had now acknowledged that, in Mr Hewitson's case, the use of recording equipment "amounted to an interference with (his) right to private life under Article 8 of the Convention and that the measures were not used `in accordance with the law' as required by the second paragraph of Article 8 and there has accordingly been a violation".

Damages rejected

Although the judges awarded costs and expenses, they rejected Mr Hewitson's damages claim, saying that he had been convicted of a serious offence.

The Government's human rights breach only related to the "lack of proper regulation" of the way the recording equipment was installed.

In addition, "there was nothing to suggest that, had procedures been in place, their use would not have been compatible with Article 8".