Banks should not refund victims of online fraud because it "rewards" them for being lax about internet security, the Metropolitan Police commissioner has said.
Sir Bernard Hogan-Howe said customers were being "rewarded for bad behaviour" instead of incentivised to update anti-virus software and improve passwords.
Police needed to focus on preventing online thefts, he told The Times.
Discussing how banks could make people more security conscious, Sir Bernard said: "That's one thing to consider. If you are continually rewarded for bad behaviour you will probably continue to do it but if the obverse is true you might consider changing behaviour."
He added: "The system is not incentivising you to protect yourself. If someone said to you, 'If you've not updated your software I will give you half back', you would do it."
His comments come as police prepare to include cybercrime estimates in official crime statistics for the first time in July.
Sir Bernard said that the figures are set to double with the change.
Two in five (44%) UK consumers have been subject to cybercrime in their lifetime, according to a survey released last year.
However two of every five (42%) do not take the time to change their account passwords after a security compromise or break, the Norton Cybersecurity Insights Report found.
Home Secretary Theresa May warned the International Crime and Policing Conference on Wednesday that faceless crime was being conducted over the internet on an "industrial scale".
But according to The Times, police follow up fewer than one in 100 frauds and there were fewer than 9,000 convictions out of more than three million frauds in 12 months.
GCHQ estimates that 80% of cybercrime, which is thought to cost £1 billion a year, could be prevented by tougher-to-crack passwords and regularly updated security software.