London (CNN) Rape victims in Britain are to be told to hand over their mobile phones and social media accounts to police or risk seeing their cases collapse, under new guidelines that have come under fire from women's rights groups and senior police figures.

New standardized forms being rolled out by police in England and Wales ask people alleging a variety of crimes, including rape and sexual assault, for permission to access their messages, emails, photographs and social media accounts, in order to improve the chances of a successful prosecution.

But the move has been condemned for "treating rape victims like suspects" and women's rights groups fear it will deter victims from coming forward to report crimes. A group that provides legal support for victims of sexual assault has also warned police they will launch a challenge in the courts to halt the strategy.

"Most complainants fully understand why disclosure of communications with the defendant is fair and reasonable, but what is not clear is why their past history (including any past sexual history) should be up for grabs," Harriet Wistrich, director of the Center for Women's Justice, said in a statement.

"We seem to be going back to the bad old days when victims of rape are being treated as suspects," she added, revealing the group's plan to challenge the approach.

Read More