Cases of identity fraud increased by more than 20% in the first three months of 2010, according to new figures from CIFAS – the UK’s Fraud Prevention Service.

During this time some 27,000 people were impersonated by fraudsters, a rise of 23% when compared with the same period last year.

Nearly 45% of these crimes were successful and not detected by the banks, CIFAS said.

The data also suggests that many criminals are now opting to use the victim’s current address rather than a previous one.

Meanwhile, consumer group Which? has warned that millions of people are still putting themselves at risk of card fraud by writing down their Pin number.

It estimates that around four million debit card holders and three million credit card holders are either keeping a note of their Pin in their wallet or handbag, or are sharing the number with a third party.

‘The results show that too many consumers are putting their finances in jeopardy by not taking simple precautions,’ said Martyn Saville, of Which?.

‘Writing down your Pin is like leaving your door open when you leave the house.’