Business Secretary Vince Cable has apologised unreservedly after sensitive documents were found in bins outside his constituency office. The unshredded papers, discovered by an unnamed member of the public, included personal details including people's names, addresses and national insurance numbers. Others included letters between ministers, Government briefing documents and a diary listing Dr Cable's meetings. The man who found the documents - who has decided to remain anonymous - told the Richmond and Twickenham Times Mr Cable's attitude to the information was "careless and irresponsible". Describing the moment he spotted the transparent bags outside the MP's office, he said: "I thought 'Am I seeing correctly or not?' and thought I better look inside. "Then I realised just how extensive it was and I just monitored it to see if it stopped." He added that some of the documents contained personal information to do with disability, health and mental problems - and gave full details of names, addresses and in some cases phone numbers. I apologise unreservedly to all my constituents for what has clearly been an unacceptable breach of their privacy. Vince Cable The Liberal Democrat MP has alerted the Information Commissioner's Office, which is looking into the matter before deciding whether to investigate. Dr Cable has written an open letter to his constituents apologising for the "unacceptable breach of their privacy". He said: "I have been alerted to a breach of data security at my Twickenham constituency office. "A system is in place for shredding of confidential files and for safeguarding case work. "Nonetheless, some correspondence which should have been protected was placed in bags for recycling outside the office. "I apologise unreservedly to all my constituents for what has clearly been an unacceptable breach of their privacy. "As soon as I heard what had happened I instructed my office to introduce a more secure system for handling sensitive information and this has now been done. "The staff responsible accept that this was an entirely inappropriate way to handle such paperwork and that this was a serious error. "I have also notified the Information Commissioner that there has been a data security breach." Meanwhile, the whistleblower The alleged data security breach is the latest embarrassment for Dr Cable. Oliver Letwin also failed to protect confidential paperwork It comes a month after he paid a £500 penalty for failing to register VAT on his freelance earnings. A cabinet minister told Sky News people "no longer take him seriously" after he told undercover Daily Telegraph journalists he had declared "war" on Rupert Murdoch. The papers were discovered by a constituent in transparent recycling bags over a nine month period, who later notified Mr Cable's local newspaper. Mr Cable said: "I am disappointed that someone went through the office recycling then hoarded the confidential and sensitive paperwork for some months rather than alerting me or a member of my staff." An ICO spokesperson said: "I can confirm that Vince Cable MP's constituency office has informed the ICO of a potential data breach and we will now make enquiries. "This is the second example in recent weeks of an MP or their staff allegedly mishandling constituency paperwork and again highlights the need to ensure that personal details are kept secure. "When constituents contact their MP they have the right to expect that the information they share will stay private - it is of paramount importance that this principle is upheld." Last month Cabinet Office minister Oliver Letwin apologised for dumping paperwork in park bins. Vanessa The Google Girl.