The Crown Prosecution Service (CPS) said it will be "exploring the reasons" for the drop in rape referrals made by police amid claims police or prosecutors are misinterpreting official guidelines.
The announcement they will be looking into the falling referral rates follows an investigation by The Independent suggesting that thousands of suspected rape cases may have been discontinued.
Since 2011 the number of rape cases referred by the police to the CPS for charging decisions has fallen by a third - despite a 3% rise in reported rapes over the period , the newspaper claims.
A CPS spokesman said the Code for Crown Prosecutors, has not changed, nor did the Director's Guidance on Charging impose new requirements on cases being referred for consideration.
In a statement, the CPS said: "The guidance simply clarified the existing requirement that cases should not be referred to the CPS for formal charging decisions if the necessary evidential standard cannot be met.
"This does not stop the police sending cases to the CPS for early advice and help on building effective prosecutions, indeed the 4th edition of the guidance specifically placed a requirement on them to do so in rape and other serious cases."
The statement added: "We are exploring the reasons for the drop in rape referrals with the police, including through a National Scrutiny Panel co-chaired by the DPP (Director of Public Prosecutions) and the National Policing Lead for Rape, DAC Martin Hewitt.
"Although this has not been raised as an issue before now, this work will include looking at the appropriate interpretation and application of the Director's guidance and the evidential standard of the case files submitted to the CPS.
"We have contacted a sample of police forces to investigate the variation in the change in volumes of rape referrals and a meeting to analyse the results of work will be held next month."
Adam Pemberton, assistant executive of Victim Support, said: "Differing referral rates across the country are cause for concern as this may mean that, in some cases, vulnerable victims are falling through the net.
"Whether a case is formally referred to the CPS should not be dependent on where a person lives in the country."
He went on: "All victims, but particularly those of serious offences like rape, want their allegation to be taken seriously and given proper consideration when they come forward to report it.
"It is vital that both police and CPS understand the impact that their decisions, at whatever stage they happen in the criminal justice process, have on victims."