Senior British politician Lord Greville Janner must appear in court in person to face a string of child sex abuse charges despite suffering from severe dementia, a British magistrate ruled.

Mr Janner 87, did not appear at Westminster Magistrates' Court in London, with his lawyers claiming he was too ill to attend the hearing over allegations that he had abused youngsters over a 25-year period.

His lawyers called two dementia experts who met him last month, who both gave evidence on the severity of the politician's condition.

However Chief Magistrate Howard Riddle decided he should attend for a formal hearing - which may last less than two minutes - in which his name and address would be confirmed, if necessary by an aide.

"Lord Janner is fit to attend," he said, even raising the rare possibility of establishing the court in the politician's home to minimise the likely distress he would suffer.

He said Mr Janner, once a top lawyer, did not have to understand the proceedings but was legally required to be present.

State prosecutors had initially declined to bring charges against Janner because they considered his dementia made him unfit to stand trial.

But after intense criticism, the Crown Prosecution Service charged him with 22 offences against nine victims, all but one of them aged 16 or under, between 1963 and 1988.

If a higher court later decides he is unfit to enter a plea, a so-called 'trial of the facts' would take place, where a jury simply decides whether the defendant committed the acts alleged. There is no decision on guilt or innocence, or possible conviction.

Mr Janner's family strongly denies claims that he used his power as a Labour MP for Leicester, the central English city he represented between 1970 and 1997, to abuse vulnerable boys at a local children's home.

Doctor James Warner, a consultant psychiatrist with 20 years' experience working with dementia, told the court that Mr Janner's condition was "severe".

He said the lord would not be able to understand he was in court, "comprehend virtually anything that was said to him", or respond meaningfully to questions.

If Mr Janner attended court a dozen times, "he would not recall having been here" - but because of this, there would be no long-term distress caused by a brief appearance.

The next hearing was set for 14 August 2015.

Following revelations about the BBC presenter Jimmy Savile after his death in 2011, a series of high-profile defendants have since faced charges of historic sexual abuse.