Personal data including the names, addresses and bank details of 27,000 Boots Dental Plan customers have gone missing after a back-up tape was stolen from the van of a security contractor.

The tape, which also contained details of the payroll accounts for around 8,000 Boots staff, was taken from the vehicle in Bristol on 3 April.

The company claimed that there is no need to worry because "specialist equipment" is needed to read the tapes.

"We would like to reassure Boots Dental Plan customers that the type of tape that was stolen, and the way the information was stored, makes it highly unlikely that any personal data could be accessed or misused," said Boots in a statement.

The high street pharmacy chain explained that Medisure, the company that administers the Dental Plan, had informed the Financial Services Authority and the Information Commissioner.

The company has CCTV pictures of the theft and is working with the police to catch the culprit.

"The police consider this to be an opportunist theft rather than a planned operation," said Medisure in the letter.

Medisure had also informed banks holding customer details, allowing them to monitor affected accounts for any suspicious activity.

Details of the data theft follow a warning from the Information Commissioner of an "alarming number of security breaches".

Information Commissioner Richard Thomas claimed that almost 100 organisations have reported data security breaches in the six months since HM Revenue & Customs had lost information relating to 25 million child benefit records.