A man who tricked his way into the home of an 15-year-old girl and raped her after answering an advertisement for a mountain bike was jailed for life yesterday.

Judge Norman Jones QC said George Braithwaite was ''a danger to young girls'' and life was the only proper sentence he could pass.

Braithwaite, 33, had targeted the young girl and ''attacked her in the most appalling manner imaginable.''

Police believe Braithwaite, who had a previous conviction for indecently assaulting a 10-year-old girl, has carried out further rapes they do not yet know about.

Detective Superintendent Andy Brown, of West Yorkshire police, said: ''This man is a potential serial rapist. He's a real danger to the public and he may well have committed further offences.

''We will be interviewing him in prison and appeal to anyone who may have been one of his victims to contact us.''

Braithwaite's victim, now 16, told Leeds Crown Court she was tied up, blindfolded and raped at her father's home in Pontefract, West Yorkshire, on December 28, 1995.

Braithwaite, of Chorlton-cum-Hardy, Greater Manchester, who denied the charge, had telephoned inquiring about a mountain bike advertised in a newspaper. He arrived wearing a crash helmet and forced his way in.

He was caught after DNA samples taken at the scene matched earlier ones from him after he was convicted of urinating in a public place. Samples were obtained then, despite the trivial nature of that offence, because of his previous conviction for indecent assault.

Judge Jones told Braithwaite:''It's impossible for me to assess what damage may have been done to that teenage girl.

''You pose a future danger to young girls and it's quite impossible for me to establish at this stage how long that danger will last.

''The only proper sentence that I can pass is an indeterminate sentence of life imprisonment.''

Mr Brown said after the case: ''He was totally deserving of a life sentence. His victim has shown much courage and fortitude and has been supported immensely by her parents.

''The family will at least derive some comfort from this sentence.''