Hundreds of innocent people could be behind bars for rape and other serious offences because of the failure to disclose crucial evidence, legal experts have said.

The warning came after the Crown Prosecution Service (CPS) was forced to drop 47 serious sex assault cases in just six weeks after a review found key material had not been shared with the defence.

The review was ordered in January this year after a string of rape cases collapsed at the last minute due to failures by the police and prosecutors to hand over evidence that could have proved a defendant's innocence.

Liam Allan, 22, a student who was accused of six counts of rape was cleared by a judge in December, after it emerged that his accuser had bombarded friends with hundreds of messages setting out her rape fantasies.