A lack of data on how many people are prosecuted for online fraud is making it difficult to pursue and prosecute criminals, according to public spending watchdogs.

Publishing the findings of its online fraud investigation today, the National Audit Office highlighted the importance of effective legal powers to prosecute criminals.

There were an estimated 1.9m cyber-related fraud incidents in England and Wales in the year to 30 September 2016, representing 16% of all estimated crime incidents. In four out of 10 online fraud incidents, victims lost at least £250.

Amyas Morse, head of the NAO, said online fraud is now the most commonly experienced crime in England and Wales. However, 'at this stage it is hard to judge that the response to online fraud is proportionate, efficient or effective', he added.

Today's report says the government wants the judiciary to make greater use of existing laws to prosecute cases. Cases can currently be prosecuted using the Computer Misuse Act 1990 or the Fraud Act 2006.

However, the NAO says the government needs to ensure current legislation 'remains applicable in the face of increasing technological change and rapidly evolving threats'. The international and hidden nature of online fraud makes it difficult to pursue and prosecute criminals because international cooperation and the ability to take action across borders are needed, it adds.

Highlighting a lack of data on prosecution numbers and concerns about sentencing, the NAO says prosecution rates are low because of the hidden nature of the crime.

'However, there is also a lack of information on judicial outcomes for fraud offences, as data cannot easily be matched across the [Home Office and the] Ministry of Justice,' the report states. 'According to some stakeholders, criminals do not always receive sentences proportionate to the crime, particularly in relation to the non-financial harm victims suffer.'

Recommendations include the Home Office working with the MoJ to improve data on fraud prosecutions and a review of sentencing guidelines.

The NAO acknowledges the 'positive step' of setting up a joint fraud taskforce last year. However, its success relies on voluntary participation from industry and law enforcement. The Home Office is urged to work with other taskforce partners, including banks and law enforcement agencies, to publish information on the taskforce's performance and future plans, and address 'intelligence gaps'.