* UK police say number of victims now reaches 300
* 114 allegations of sex crimes made so far
* "Tsunami of filth" has rocked the BBC (Adds more details)
By Michael Holden
LONDON, Oct 25 (Reuters) - British police investigating alleged sexual abuse by one of the BBC's most celebrated TV stars said on Thursday some 300 victims had come forward and they were preparing to make arrests in a scandal that has thrown the broadcaster into disarray.
Detectives said they had been staggered by the number of people who had come forward since the late Jimmy Savile's crimes were first revealed just over three weeks ago.
The head of the BBC's governing body called the allegations a "tsunami of filth", and police said Savile was "undoubtedly" one of Britain's most prolific sex offenders ever.
"It's quite staggering," said the police inquiry leader, Commander Peter Spindler.
Having interviewed 130 of the alleged victims, officers had recorded 114 reports of sexual assault or serious sexual assault, mostly against Savile - the outlandish, cigar-chomping DJ turned TV host who was one of the BBC's top presenters of the 1970s and 1980s.
The allegations, which first emerged in an expose on the rival British TV channel ITV, have rocked the BBC, with its chief George Entwistle admitting the broadcaster has been damaged by the scandal.
The revelations have generated huge attention, not least in the United States where Entwistle's predecessor at the BBC, Mark Thompson, is poised to take over as chief executive of the New York Times.
On Wednesday, lawyers representing some 30 alleged victims of abuse told Reuters their clients said other celebrities were involved, while some of those abused by Savile have told the media they were targeted on BBC premises.
"We are preparing an arrest strategy now," Spindler told reporters, adding he could not identify who their suspects were or whether they also had worked for the BBC. "We do have a number of other people that we can investigate."
Entwistle, who only took over the most prestigious role in British media in September, appeared before a parliamentary commission this week to explain why the BBC had dropped its own investigation shortly after Savile died last year.
His performance in parliament was described as "lamentable" by one lawmaker, and his overall handling of one of the worst crises in the BBC's 90-year history has been widely condemned.
Prime Minister David Cameron has said the BBC, paid for by an annual tax on all households with a colour TV, had serious questions to answer.
"We have to deal with the terrible damage to the reputation of the BBC which has hitherto been a national institution which people have trusted," Chris Patten, chairman of the BBC Trust which oversees the broadcaster, told BBC Radio.
"It was a very, very difficult initial baptism of fire for a new director general of the BBC, this great tsunami of filth broke over him 11 days into the job."
Savile, knighted by Queen Elizabeth for his charity work and famous for his garish outfits and long blonde hair, was a household name in Britain but little known beyond its shores.
Such has been the publicity surrounding the case that Spindler said the number of historic abuse allegations reported to police in London alone had trebled, calling their inquiry a "watershed moment for child abuse investigation".
He said they were investigating three categories of offences; those that involved just Savile which made up the vast majority of cases; those involving Savile and others; and those which had no direct link to Savile.
At this stage there was no evidence of any organised paedophile rings and offenders appeared to be opportunists, Spindler added.
He revealed that a retired officer had come forward to say he had investigated Savile in the 1980s over allegations of indecent assault but there had not been enough evidence to pursue a prosecution. (Additional reporting by Stephen Addison; Editing by Maria Golovnina)