That's incorrect. The UK government did a study of this, which can be found here:
http://webarchive.nationalarchives.gov.uk/20100408125722/htt...
The study is deeply biased, doesn't try to hide it and quite clearly tries to tell politicians what they want to hear. Nonetheless it has a lot of useful data and states two things of interest in this thread:
1 - the false reporting rate is stated as being about 10% in the UK.
2 - all police interviewed for the the study believed that figure was far too low.
With respect to point (1) - once again this is a very, very generous definition of "false". For instance it doesn't include cases where someone reports a rape on behalf of the alleged victim and the alleged victim later states that no rape in fact took place. This is clearly a false accusation and it'd be just as distressing to the accused, but isn't counted as false.
The inconsistency between the figures the study reports and the perception of police themselves is noted and discussed in the study:
"Even if all those designated false by the police were accepted (a figure of approximately ten per cent), this is still much lower than the rate perceived by police officers interviewed in this study"
Example quotes from working police officers:
"I do deal with a lot of allegations that don’t go anywhere, because it transpires that
it’s not quite a rape, certainly with juveniles ... we spend a lot of time dealing with allegations of rape that really aren’t rape, that take a lot of time up. I would say a good half that come through are not genuine ones."
A different officer:
"We have a lot of allegations that are then retracted, we have a lot of allegations that
it comes out in the wash one way or another that it was consensual."
And a different one:
"Well, honestly, it’s because most of them are not telling the truth ... I mean I have dealt with
hundreds and hundreds of rapes in the last few years, and I can honestly probably count on both hands the ones that I believe are truly genuine."
There are no quotes or interviews with police officers who believe the 10% figure is accurate or think it's too high.