Young people who post images their driving test pass certificates online are increasingly at risk of suffering identity fraud, a police chief has warned.

City of London Police Commissioner Ian Dyson warned social media plays a "significant role" in online fraud, and is an area where young people are more vulnerable than older generations.

He used the example of young people falling victim to identity fraud after posting pictures online of their newly-gained driving licence or passport online.

Asked why the country's different police forces vary so widely in how they tackle online crime, he said its "hidden nature" means it is given far less focus than violent crime.

His comments came during an evidence session into internet and con tricks by criminals to obtain people's funds to MPs.

A fraud expert at Lloyds Banking Group said some bank customers are still being duped despite being warned by their bank that it may be a scam.

Brian Dilley, group at the firm, said customers are increasingly becoming victims of authorised push payments.

Many are not able to recoup their money as they have transferred it themselves.

Unlike scams where a fraudster takes money from their victim's account without their knowledge, with authorised push payment fraud the customer has given their consent for the payment to be made as they have been tricked into believing they are paying a legitimate payee.

Giving evidence to the House of Commons Public Accounts Committee (PAC), Mr Dilley said: "I think the emerging threat is the authorised push payments - so the authorised fraud.

"From our perspective, that presents itself as - it is the customer who is asking to move the money."

He said customers often do not get their money back as "there is a limit to what we can do".

"There are plenty of examples as well of where we have warned the customer that we think it's a scam but they insist on us processing the payment," Mr Dilley said.

"It's happened surprisingly regularly."

Questioned by the committee on why high street banks are not more transparent on how many of their customers fall victim to fraud, he said it would not be wise to publish such information.

Mr Dilley said: "If you could compare the numbers and see which was the weakest of the banks, that's where the fraudsters would go to. It would encourage the fraudsters to direct their activity towards the weakest area.

"Each bank does know how they compare, so they know their own numbers compared to the industry numbers. So we know how we compare against others and that is used internally to improve our processes."

Home Office ministers have set up a joint fraud taskforce to help co-ordinate a response to the vast and growing problem of online crime, but this was described as "shambolic" by committee chairwoman Meg Hillier.

Permanent Secretary Philip Rutnam told MPs that more could have been done to share information earlier, but added: "I think there has actually been an awful lot going in the joint taskforce and an awful lot has been shared around that."