The BBC's Mike McKay reports

The offences took place between 1972 and 1978 when Cooke, 72, preyed on youngsters as he travelled across the country working on fairgrounds.

"Hissing Sid" set up children's Test Your Strength machine in fairgrounds, using the opportunity to meet boys and lure them into homosexual orgies.

Cooke, habitually dressed in a filthy suit and trilby hat, was one of a 1980s gang of four jailed for killing of runaway Jason Swift, 14, in a squalid flat at Hackney, east London.

He was sent to prison for 19 years in 1989, but was freed in April last year after his sentence was cut by Appeal Court judges.

Cooke was housed in police cells following public anger at his release.

Documentary

But earlier this year he was arrested by detectives investigating allegations of serious sexual offences which had come to light after a Channel 4 documentary, Dispatches.

Jason Swift was killed in a squalid Hackney flat

Cooke admitted five counts of indecent assault and five counts of buggery when he appeared at Manchester Crown Court on Tuesday.

He also denied four counts of rape as well as three further counts of indecent assault and one of buggery dating to 1981.

Mr Justice Poole ordered those charges to lie on the file.

Both brothers were teenagers when they were assaulted by Cooke - one over a four year period and the other over a two-year period.

'Natural relationship'

Sir John Nutting QC, prosecuting, described how for part of their formative years the children were brought up in homes because their mother could not cope.

He said: "Cooke systematically embarked on a course of sexual abuse, so frequent and so manipulative that the boys came to regard a sexual relationship as the natural relationship between adult and child.

"Assault and buggery were the stock-in-trade of the defendant's relationship with them."

Sir John told the court that Cooke blamed his actions on what he had suffered himself as a child.

"He claimed to police in interviews this year that because he himself had suffered abuse as a young boy, he considered that when he abused the two boys he had behaved naturally."

'I will never forgive him'

The older brother later told police that Cooke had ruined his life through the systematic campaign of abuse waged against him.

The victim told the police: "I feel that the treatment I suffered during my childhood and teenage years has caused me much suffering and mental anguish and has destroyed a lot of my relationships.

"I will never be able to forgive Sidney Cooke for what he did to my family."

Sentencing was adjourned for a month to await psychiatric reports.