Investors with money in the Fidelity FundsNetwork were told yesterday that the stolen information includes names, addresses, date of birth, National Insurance numbers, fund investment details – and even how much each person had invested.

The Yorkshire Post understands the laptop was taken from a locker being used by a staff member of an information technology (IT) consultancy employed by Skipton Financial Services.

Moore Stephens Consulting was carrying out work on an IT system for the Yorkshire-based investment company when the theft took place on Tuesday evening last week

This latest security lapse comes just days after the details of three million learner drivers were lost in Iowa, USA, and an information cartridge containing details about 6,500 pensioners was misplaced by HM Revenue and Customs.

Both scandals came to light after HM Revenue and Customs lost two CDs containing the bank account data of 25 million recipients of child support benefits.

These recent fiascos could lead in future to more prosecutions under the Data Protection Act, which allows a fine to be imposed against someone who is found to have wrongly released sensitive data.

Last night a Skipton spokesman stressed that the laptop was password-protected and all affected accounts with Skipton Financial Services had been immediately suspended.

Managing director Simon Holt wrote to all 14,000 customers apologising for the breach of security and assuring them that an investigation had been launched.

Mr Holt yesterday denied that his company had any responsibility for the loss of the laptop and said every possible step had been taken to reduce risk to clients.

National Consumer Council spokeswoman Diane Gaston said: "It seems companies and the Government have not yet got used to having our information in a digital age. They need to make sure their security processes are robust and are followed.

"It can be an absolute nightmare being a victim of identity theft – you have to notify your banks, your building society, utility companies and everyone else you pay bills to.

"People need to make sure they check their bank balances and ask for credit checks."

Skipton Financial Services told their customers about the missing data after advice from the Information Commissioner's Office, for whom a spokeswoman said an investigation was under way.

A spokesman for the regulatory Financial Services Authority, Robin Walker, said: "Skipton Financial Services have kept us informed and we know what has gone on.

"People in possession of information about customers have an overall duty to keep information about those customers safe and secure."

The managing partner of Moore Stephens, Colin Moore, said his firm was doing everything it could to protect data and review security procedures.

A helpline for people whose details might have been taken is open from 8am to 8pm Monday to Friday on 0800 137832.