Allegations that a secret undercover police unit carried out spying operations on Labour MPs need to be investigated immediately , Nick Clegg demanded this morning . The Deputy Prime Minister said the idea that elected politicians were being 'snooped on ' because of their views 'appalled ' him and urged the Home Secretary Theresa May to order a wider probe into undercover police tactics to investigate allegations . It comes after a former officer , Peter Francis , said he read files on 10 MPs during his 11 years working for the Metropolitan Police 's now notorious Special Demonstration Squad . The Deputy Prime Minister said the idea that elected politicians were being 'snooped on ' because of their views 'appalled ' him . He said the files included Labour 's now deputy leader Harriet Harman , former cabinet minister Peter Hain and Jack Straw , later home secretary . Details about the targets were collected by officers infiltrating anti-racism and other left wing political groups , and apparently continued after they were elected to Parliament . The former officer claimed he personally collected information on Diane Abbott , Jeremy Corbyn and the late Bernie Grant and said special branch collected intelligence on Ken Livingstone , Joan Ruddock , Dennis Skinner , and Tony Benn . The pink files were 'very extensive ' he said , and included details of a subject 's political beliefs , family relationships , personal background , education , and finances . Some contained details of 'personal and private matters ' , he said . If true , the files on many of the subjects existed years after they entered Parliament . Four of those on his list became ministers during his time in Special Branch . The revelations prompted demands for a forthcoming public inquiry into undercover policy to be widened to include the new allegations . Speaking on LBC this morning , Mr Clegg said the allegations , if true , were 'absolutely terrible ' . He said : 'The idea that the police snooping and monitoring elected politicians in effect because of their views - because they were deemed to be from the left , that they were somehow dodgy - it absolutely appalls me . ' I know there 's an inquiry into undercover police tactics and I very much hope it will look at these allegations because they are not the kind of thing you want in a free society . 'Politicians , regardless of their views , should be able to represent their constituents and express their opinions without being monitored by the police . ' A secret undercover police unit carried out spying operations on now deputy Labour leader Harriet Harman ( left ) and former foreign secretary Jack Straw . Mr Francis was an undercover officer between 1993 and 1997 in the now disbanded Special Demonstrations Squad . He infiltrated left wing groups and causes which were deemed to potentially pose a threat to national security . He told the BBC : 'When I was deployed undercover in the Special Demonstration Squad , any MP that I came across , such as on demonstrations , I would report back on them ' . 'When they became MPs these files carried on . It [ was ] your duty as an SDS officer to report back any intelligence that you come across . ' ' I felt that it was OK to report back on MPs , ' he said . ' I used to give myself a pat on the back , thinking ' I have done a good job ' . These MPs were spied on and they should know . ' ' I do n't think the police force should be monitoring MPs , full stop . I do n't think we have any right to do that at all . It may be justifiable to say that the Security Service should be doing it - but I certainly do n't think the police should be doing it . ' Mr Hain told the Guardian : 'That the special branch had a file on me dating back 40 years ago to anti-aparthied and anti-Nazi League activist days is hardly revelatory . 'That these files were still active for at least 10 years while I was an MP certainly is and raises fundamental questions about Parliamentary sovereignty . ' Scotland Yard pointed out that Operation Herne the internal police investigation into the unit was still ongoing , but that Mr Francis had refused to speak to it about his claims . A former officer said he read files on 10 MPs during his 11 years working for the Special Demonstration Squad including Diane Abbott ( left ) and special branch collected intelligence on Dennis Skinner ( right ) Special branch also investigated Former London Mayor Ken Livingstone ( right ) and former Welsh secretary Peter Hain ( left ) who said the files raised 'fundamental questions ' about Parliamentary sovereignty . A Met spokesman said : 'Operation Herne has previously reported publicly on SDS methodology and remains a live ongoing investigation . 'Operation Herne maintains that without speaking to Peter Francis it is simply not possible to fully investigate allegations he makes . Operation Herne remains very willing to engage with him . ' The taxpayer faces a compensation bill running into the tens of millions of pounds from miscarriages of justice linked to a the SDS . Hundreds of animal rights activists , neo-Nazi groups , campaigners for black justice and other campaigners who , unknowingly , were spied on by the Special Demonstration Squad could have their convictions overturned . Women have also sued the Met after having children with undercover officers who they thought were genuine protesters .
A former officer from a secret police unit admitted spying on Labour MPs . Targets included deputy leader Harriet butler , Peter Hain and Jack Straw . mark Clegg this morning said the allegations , if true , were ' terrible ' and Prime Minister ordered a probe into police tactics to investigate them .