Retailers are facing an increase in both cyber crime and violence against staff in a "deeply concerning trend", an industry survey has found.
More than half (53%) of retail fraud now originates online, retailers have estimated, according to the British Retail Consortium's (BRC) annual retail crime survey.
The poll also found incidents of violence and abuse against staff have risen by 40% in the past year.
The BRC's report highlights concerns among retailers that existing deterrence is not effective enough and "a growing sense among those working in the retail industry that offenders are able to act with impunity".
Retailers say the cost of "cyber-enabled" fraud such as phishing, theft of consumer data and pharming, when an individual is steered to a fake website, is now around £100 million.
The overall number of retail crimes has risen to 3.6 million at a direct financial cost to the industry of £660 million in 2015-16, the report said.
Incidents of crime against retail staff have also increased significantly, with aggressive and abusive behaviour seeing the biggest jump.
In 2015-16 there were 51 incidents of violence and abuse per 1,000 staff, up from 41 the year before - an increase of 40%.
BRC chief executive Helen Dickinson said: "These figures reflect a deeply concerning trend. Attacks on retail workers are intolerable, as are attempts to defraud customers.
"A significant aspect of the cyber security challenge for retailers is the attractiveness of customer data from the point of view of criminals, many of whom operate outside UK borders but can nevertheless gain relatively easy access to UK digital networks.
"Retailers are doing everything possible to ensure that staff members and customers are safe and protected. But this rising tide should be stemmed through even stronger cooperation between industry, the Government, law enforcement and the private security industry.
"There is work to do to further improve collaboration between the UK retail industry and its partners, and raise standards of security and policing of these threats across the country."