A secretive police unit tasked with spying on alleged extremists intent on committing serious crimes has been monitoring leading members of the Green party, the Guardian has learned.
Newly released documents show that the intelligence unit has been tracking the political activities of the MP Caroline Lucas and Sian Berry, the party’s candidate for London mayor.
Some of the monitoring took place as recently as last year and seemed to contradict a pledge from Sir Bernard Hogan-Howe, the Metropolitan police commissioner, that the unit would only target serious criminals rather than peaceful protesters.
Extracts from the files show that the police have chronicled how the Green politicians had been speaking out about issues such as government cuts, the far right, police violence, and the visit of the pope.
The police’s actions have been described as “chilling” and come weeks after it was accused of abusing its powers by pursuing prominent people over sex abuse claims.
The disclosures bring to four the number of elected Green party politicians whose political movements are known to have been recorded in the files of the unit. The files give no indication that they were involved in serious criminal activity.
The file on Lucas, which stretches over eight years, records how she gave a speech at an anti-austerity demonstration last June in London. Lucas accused the government of conducting an “ideological war on welfare” at the rally, attended by thousands.
Another entry records how she attended a demonstration in February 2014 against disability cuts in Brighton where she has been an MP since 2010. Police noted she “spoke with some of the assembled” journalists.
She is also logged as attending a demonstration in Brighton in April 2014 opposing a far-right march in the city.
Lucas said: “Spending precious resources on monitoring elected politicians is a clear waste of the public’s money – and sends a chilling message to those who want to engage in peaceful political demonstrations. Nobody should be subject to arbitrary surveillance.
“It’s this kind of thinking that has led police in this country to waste vast amounts of taxpayers’ money in infiltrating environmental groups. The police should focus resources on fighting real crime, not attempting to stifle legitimate protest.”
The file on Berry notes that she gave a speech as “the Green mayoral candidate” at 10am at an event that has not been specified.
Berry said she believed it was a Green party conference last September as she had given only one speech once at that time since becoming the candidate that month. Police declined to say if this was the case, or whether the information came from the internet or a covert police presence at the conference.
Another entry in the file recorded that she signed an open letter in the Guardian insisting that Pope Benedict should not be given the honour of a state visit to Britain in 2010. Other signatories included the authors Stephen Fry and Terry Pratchett.
Police also logged her unsuccessful attempt to be elected to Camden council in north London in 2006. She was elected to the council two years ago.
Berry, who would have political responsibility for London’s police if she became mayor on 5 May, said: “It appears that the Met has learned nothing from the scandal of undercover policing and the monitoring of campaigners like the Lawrence family. As mayor I would want the Met police focused on catching serious criminals and terrorists, not wasting time and our money snooping on Green politicians and campaigners who they think might want to change the status quo.”
The police’s domestic extremism unit – which operates across the country and is based within the Met – has kept files on thousands of protesters, saying that it needed to identify those who use, or may use, criminal methods to further their political aims.
However, police have faced criticism for tracking campaigners who have not committed crimes and for storing mundane information, such as the sale of political literature by an activist at the Glastonbury music festival.
Hogan-Howe has said that in October 2013, the unit tightened up its procedures so that it would focus on individuals who commit or plan “serious criminal activity motivated by a political or ideological viewpoint”. He said it would usually exclude “low levels of civil disobedience such as civil trespass or minor obstruction”.
Three of the four Green politicians – including Ian Driver, who was monitored between 2011 and 2014 while he was a Kent councillor and Baroness Jenny Jones, the Green’s candidate for London mayor in 2012 – do not have a criminal record.
Lucas was fined for breaching the peace after she and other demonstrators blocked traffic outside a nuclear weapons base in 2001. She was acquitted of public order offences at an anti-fracking protest in Sussex in 2013.
The police file also records how she took part in environmental demonstrations in 2008 and 2009, while she was an MEP.
Asked why the files had been compiled, a spokeswoman for the unit – now known as the National Counter Terrorism Police Operations Centre – said: “We do not discuss details of records which may or may not have been compiled in relation to named individuals.”
She said it “gathers data for policing purposes in accordance with UK law. The centre fully complies with stringent data protection legislation in regard to the collation, retention and deletion of records.”
It was previously revealed that the police unit kept a file on the political life of Jones between 2001 and 2013. During that time, Jones, a London councillor, was on the official committee scrutinising the Metropolitan police.
David Williams, a whistleblower from the domestic unit, has alleged that police improperly destroyed files they had compiled on Jones in a “highly irregular” cover-up – a claim denied by the Met.
The file on Jones documented how she had given speeches at public meetings about issues such as police violence and Conservative cuts in public spending.
The quartet obtained the files on themselves by submitting requests under the data protection act, although police have not said whether the full files were released.
Peter Francis, a whistleblower who worked undercover for the Met, has alleged that the police kept secret files in the 1990s on 10 Labour MPs, including the Labour leader, Jeremy Corbyn, after they had been elected to parliament.