The UK parliament has demanded to know why Facebook has decided to exempt political statements from its fact-checking programme – removing all bars on political candidates lying in paid adverts.

In a letter to the former deputy prime minister Nick Clegg, now Facebook’s vice-president for global affairs and communications, Damian Collins, the chair of the House of Commons’ digital, culture, media and sport select committee, described the change first reported in early October as “particularly concerning”.

Collins wrote to Clegg with five questions for Facebook to answer, three of which covered the rule change. “Why was the decision taken to change Facebook’s policy,” the MP asked, “given the heavy constraint this will place on Facebook’s ability to combat online disinformation in the run-up to elections around the world, and a possible UK general election in particular?”

Collins also queried the role of Facebook’s global elections integrity operations team in the decision-making process. Citing a Twitter thread Yaël Eisenstat, in which she said she had previously suggested scanning ads for misinformation to “silent” responses from her bosses, Collins asked: “What proposals has [the team] made, to what extent were these proposals determined to be feasible, and on what grounds were they not progressed?” Collins also asked about whether Facebook would be formalising its relationship with its third-party fact checkers “in the long-term”.

The committee’s letter comes after Facebook’s vice-president, Richard Allan, announced the company’s plans for a possible UK general election in the next few months. Writing in the Telegraph, Allan promised a “dedicated operations centre” in the UK if an election is declared, to quickly remove content that breaks Facebook’s rules, such as misleading information about the mechanics of the election, or content aimed at encouraging users not to vote at all.

Allan also promised a dedicated channel to report harassment for MPs and prospective parliamentary candidates, and a wider selection of adverts contained in the site’s ad library, which will now store adverts about issues including immigration, health and the environment, as well as elections and referenda, as it previously did.

Collins’s letter comes on the heels of a major series of announcements by Facebook designed to plan for a US election in 2020, including stricter rules on disclosing who controls a popular page, and new bans on political adverts that attack democracy in general.