Data privacy campaign groups and Labour have expressed alarm after it emerged Downing Street has ordered departments to centralise the collection and analysis of user information from the government’s main public information website ahead of Brexit.

While officials insist the move to share user data from the Gov.uk website is simply intended to improve the service and that no personal details are collected, campaigners raised concern about the urgency of the task, and the personal involvement of Boris Johnson and his chief adviser, Dominic Cummings.

A leaked memo last month from Johnson to ministers on the cabinet committee tasked with no-deal preparations, known as exit operations, or XO, specifically linked the gathering of the user data to government decision-making over Brexit.

The memo, seen by BuzzFeed, said the XO committee had been tasked with making sure Gov.uk “is serving as a platform to allow targeted and personalised information to be gathered, analysed and fed back actively to support key decision-making – in effect, focused on generating the highest-quality analytics and performance data to support exit preparations”.

Johnson ended the memo, sent on 19 August, by writing: “I expect everyone to act immediately to execute the above actions.”

Nine days later Cummings, who has been the focus of concerns about the use of voter data by the official Vote Leave campaign in the 2016 Brexit referendum, emailed officials to stress this was a “top priority”, BuzzFeed said.

Profile Who is Dominic Cummings? Show Dominic Cummings, the son of an oil rig project manager and a special needs teacher, was born in Durham in 1971. He attended a state primary school followed by the fee-paying Durham school and, in 1994, Oxford University, where he studied ancient and modern history. After three years living in Russia, where he attempted to set up an airline connecting Samara in the south with Vienna, the then 28-year-old became campaign director of Business for Sterling, which worked to prevent Britain from joining the euro. Although he has never, as far as anyone knows, been a member of a political party, Cummings was headhunted to be director of strategy for the then Conservative leader, Iain Duncan Smith, in 2002. While he was seen as a “young, thrusting moderniser”, Cummings quickly offended party traditionalists. He quit the job after only eight months, describing Duncan Smith as incompetent. Following the 2010 general election, the then education secretary, Michael Gove, appointed Cummings as his chief of staff. Many in Whitehall found Cummings as difficult as he found them. In 2013, civil servants in the Department for Education complained to the Independent of an “us-and-them, aggressive, intimidating culture” created by Cummings and Gove. He never hid his disdain for the workings of Whitehall and has derided Westminster figures in eye-catching media interviews and published rambling blogposts that are obsessed over by Westminster insiders. He described prime minister David Cameron as “a sphinx without a riddle”, and former Brexit minister David Davis as “thick as mince, lazy as a toad, and vain as Narcissus”. In 2015, Cummings and the political strategist Matthew Elliott founded Vote Leave, which was designated by the Electoral Commission as the official EU referendum leave campaign in April of the following year. Since the EU referendum, its tactics have been the subject of a series of high-profile scandals. Vote Leave’s use of data analytics has been scrutinised after the Observer reported that the data-mining company Cambridge Analytica had links to the Canadian digital firm AggregateIQ, on which Vote Leave spent 40% of its campaign budget.

In July 2018, the Electoral Commission announced Vote Leave had been found guilty of breaking electoral law by overspending, following testimony from whistleblowers. The group was fined £61,000 and referred to the police.

Cummings has used his blog to furiously defend himself and the Vote Leave campaign. In March 2019, he was found in contempt of parliament for refusing to appear at a committee of MPs investigating fake news. Frances Perraudin

Tom Watson, Labour’s deputy leader, said: “This centralised harvesting of citizen’s data is very suspicious. Why would Dominic Cummings say this was a top priority for the government, given the national crisis we are in? We need immediate assurances about what this data is going to be used for.”

Silkie Carlo, the director of privacy campaign group Big Brother Watch, said: “This data grab raises important questions as to the legitimacy, urgency and purpose of such personal information collection. The government must answer these questions urgently.”

The claim that no personal data would be collected “is at odds with its instruction that government websites should urgently gather ‘targeted and personalised information’,” Carlo said.

“This secret instruction and contradictory public statement is cause for concern and undermines public trust at an important time. People need to be able to access government information without worrying about how their data might be tracked, recorded and used.”

Dominic Cummings reportedly told officials the data collection was a ‘top priority’. Photograph: Toby Melville/Reuters

Pascal Crowe from Open Rights Group, which campaigns on digital privacy and freedoms, said: “This decision completely disregards the data rights of ordinary citizens. There is no suggestion of public consultation, seeking consent or promoting safeguards.

“The public conversation around the use of data has shifted since the Cambridge Analytica scandal. Where is the public’s consent for this? Dominic Cummings may claim to be a pioneering advocate of data science, but when it comes to its ethical use, he is woefully behind.”

Officials have said the only difference will be that anonymised user data currently collected by individual departments will now be collated across the Gov.uk website, allowing better information on how the site is used as a whole.

A government spokesman said: “Across the industry, it is normal for organisations to look at how their websites are used to make sure they provide the best possible service.

“Individual government departments currently collect anonymised user data when people use Gov.uk. The government digital service is working on a project to bring this anonymous data together to make sure people can access all the services they need as easily as possible.

“No personal data is collected at any point during the process, and all activity is fully compliant with our legal and ethical obligations.”