A corruption trial involving North-East police officers and one of the world's biggest drug barons collapsed yesterday after a judge threw out phone tapping evidence.

In a case that could have far reaching national implications, a judge ruled that secret tape recordings could not be used against international drug smuggler Brian Charrington and three Cleveland Police officers.

Charrington, a convicted international drugs baron wanted in two other countries, had been charged along with Detective Sergeant Ian Weedon, retired Detective Sergeant James McSorley and Detective Constable Paul Hardy over an alleged conspiracy to obtain sensitive information held on police computers.

But, following two weeks of legal argument at Leeds Crown Court, Judge Kerry MacGill decided the defendants would not get a fair trial.

He ruled that, under a section of the Regulations of Investigatory Powers Act 2000, together with Human Rights implications, he could not allow the evidence of telephone recordings to be used in evidence.

The Act, which replaced the Interception of Communications Act 1985, regulates the powers of security services to carry out surveillance and intercept telephone calls.

Legal experts are now to consider the ruling. They fear the setback may have widespread implications.

Lawyers for the Crown Prosecution Service are studying the judgement to see if it could result in the failure of other cases against alleged armed robbers, drug dealers, murderers and terrorists, which depend on the interception of telephone conversations.

They could take their case to the Attorney General and the Court of Appeal.

And if the Court of Appeal backs the judge's decision, Cleveland Police said last night there could be calls for the law on covert surveillance to be changed or even scrapped.

The trial - stemming from a Cleveland Police probe code named Operation Teak - collapsed because the phone-tapping laws had changed since the tapes were made.

Ironically, Operation Teak was launched after an earlier trial involving Charrington, a former Middlesbrough car dealer, collapsed in 1993.

Then, Charrington escaped prosecution after leading Regional Crime Squad officers and Cleveland Police detectives said he was a key informant - a fact not passed on to customs officers who had brought the case.

After being unmasked as a so-called "supergrass", Charrington and his brother, David, were both given a new home - at taxpayers' expense - in Australia.

But he returned to Europe and holed up in a Spanish villa. There, he later faced extradition to France where he is wanted for his part in a £2m drug smuggling operation.

He was arrested after police were tipped off as he tried to sneak back into Britain last year.

Charrington and his three co-accused had denied conspiring together to obtain sensitive information held by police, the disclosure of which was prejudicial to the public interest.

But yesterday, Judge MacGill sensationally threw the central plank of the prosecution's case out.

After examining the evidence he said: "My interpretations of the law are mine and mine alone. It in no way reflects on the police activity in bringing this case.

"The evidence was gathered in 1996 under the rules and regulations that existed then. The law has changed.

"I take the view that changes brought about by Parliament have made a fair trial impossible."

Stephen Williamson QC, prosecuting, said that because the phone-tapping evidence could not be referred to, let alone admitted, the crown had decided to offer no evidence against the accused men.

He added: "No blame should fall on the police or Chief Constable Barry Shaw who instigated the inquiry.

"Parliament has moved the goal posts since the telephone evidence was obtained. It has substantially altered the law in a far-reaching way."

A Cleveland Police spokesman last night confirmed DS Weedon, 46, who comes from Teesside, and DC Hardy, 42, who lives in County Durham, both remain suspended. They face possible disciplinary charges.

DS McSorley, 54, of Teesside, will face no further action after he retired on medical grounds in 1999.

Last night, Charrington was being held in custody while extradition proceedings were launched to have him sent to Germany over drug offences.