Victims of sexual assault may be less likely to come forward if personal information from their phones is shared as evidence in court, over fears they may be blamed for their attack in the 'digital equivalent of a short skirt'.

Sara Thornton, chairwoman of the National Police Chiefs' Council, said evidence disclosure is important, but insists that officers must balance that against the risk of discouraging victims.

Charges and prosecutions for sexual offences remain below average when compared to other crimes in the UK.

Last year, police forces were hit by several cases where errors in evidence disclosure led to the collapse of sexual assault trials.

Sara Thornton, chairwoman of the National Police Chiefs' Council, says victims of sexual assault may be discouraged if their personal phone data is shared in court

Ms Thornton told The Times: 'We don't want this to make victims feel that they can't report offences because they fear the intrusion into their private life and their private information because they fear that that will either be shared by the defence inappropriately or be dealt with in court.

'That's where we came to the equivalent of the digital short skirt — this idea that we must be reassuring victims that information which is nothing to do with the case would never be used to discredit them in the way that the idea of a woman's dress in some way [is used to suggest] she's responsible.'

More than 900 criminal cases were dropped in 2017 due to a failure by police or prosecutors to disclose evidence.

The series of failures led former Lord Chief Justice, Igor Judge, to warn that juries may start to think they have not been shown all the evidence, and victims to not come forward.

In 2018, dozens of prosecutions for rape or serious sexual offences were thwarted because of issues with the disclosure of material.

The cases led to accusations that police officers were 'cherry picking' evidence in order to force a conviction and create a narrative.

These events led to widespread scrutiny on the police and calls for improvements in the process.

However, while acknowledging he need for police to do better, Ms Thornton has warned of the risk of disclosing too much personal information, which may leave victims too scared to come forward and share evidence.

She added: 'It's essential that investigators are open-minded and fair, they have a duty to be fair.'