Claims that the man who committed most of the Yorkshire Ripper murders may still be free will be put to the Irish Government.

A former Irish justice minister will press West Yorkshire police to reopen the investigation into the horrific murders between 1975 and 1980.

Sean Doherty, who was Minister for Justice in the Irish Republic at the time Bradford lorry driver Peter Sutcliffe was caught in 1981, said an independent examination of the facts was needed.

Mr Doherty will ask the present Irish Minister of Justice, Michael McDowell, to urge the British authorities to re-examine the case after studying claims in a book by Irish author Noel O'Gara.

Mr O'Gara, 60, of Balli-nahown, County Westmeath, claims Sutcliffe was a copy-cat killer and committed only four of the 13 murders. He believes there was a police cover-up.

He alleges the real Ripper is a stocky, bearded Irishman - his former friend and employee - and is still in the UK.

Mr Doherty told the Telegraph & Argus: "The book caused me considerable concern. There is, in my opinion, a prima facie case for a re-examination to establish the facts.

"It's my intention to make submissions to the Minister of Justice. I'm going to write to him and submit the material and express my concerns."

In his book, The Real Yorkshire Ripper, Mr O'Gara names the man he alleges was responsible for most of the savage killings. The Telegraph & Argus cannot name him for legal reasons.

He claims the man was the one who sent three letters and the "I'm Jack" tape, taunting police.

Mr O'Gara said he had been reading a psychological profile of the Ripper in a newspaper in November 1979 when he realised the man he knew was the probable suspect.

He wrote: "The portrait the article painted encapsulated him. He was the only man that could do it.

"Here was a violent, dangerous and aggressive psychopath with a long criminal record, mostly in England, who had intimate knowledge of prostitution in every city in England, who was totally unselective in his approach to women.

"He was living in Ireland. I could clearly and easily see that this was no impediment to him.

"On the other hand it was his perfect cover and was the obvious reason why the police couldn't catch him in England.

"I was shocked and I was terrified but I knew from that moment it was him."

Mr O'Gara flew to England to see detectives but, he said: "It was the most valuable tip-off in the history of crime and they laughed at me."

He said Sutcliffe had been questioned and eliminated a dozen times before his arrest in 1981, because his blood group did not match evidence found on the bodies. He said that, before the arrest, a number of senior Ripper Squad officers openly admitted there was not one Ripper but two.

After Sutcliffe's conviction Mr O'Gara met the head of the Ripper Squad, Assistant Chief Constable George Oldfield, along with Detective Chief Superintendent Dick Holland at a Wakefield hotel.

"He gave them an item of underclothing belonging to the man he suspected of at least nine murders but failed to convince them.

Mr O'Gara told the T&A: "I think the public shouldn't be kept in the dark over such a matter. They've been fooled up to the eyeballs. I'm convinced this man is still at large in the UK. You wouldn't want a man like that living in your neighbourhood."

"I put the facts together and I wrote the book. The fact that the police did nothing about it is their business."

Mr O'Gara said he had not been in contact with the man he suspected for several years.

But, he said, he believed the "real Ripper" had killed at least once more, in the North Midlands. Former Detective Chief Superintendent Dick Holland, who was demoted to a uniformed post after Sutcliffe's trial and retired in 1983, rejected Mr O'Gara's claims.

Mr Holland said the item of clothing Mr O'Gara gave him had been closely examined by forensic scientists and found not to be linked to evidence from Ripper victims.

"The man Mr O'Gara put forward was eliminated," he said. "He wasn't interviewed as he was in the Irish Republic. I'm absolutely certain Sutcliffe committed all the murders with which he was charged."

Mr Holland said immediately after Sutcliffe's conviction a top level team of police and other experts, headed by Chief Inspector of Constabulary Sir Lawrence Byford, systematically sifted all the evidence.

Their thorough review of the entire Ripper case had not indicated more than one killer was involved.

West Yorkshire Police declined to comment on Mr O'Gara's allegations.