The UK’s Information Commissioner welcomed Facebook’s decision to end its partnerships with several large data brokers who help advertisers target people on the social network.

Elizabeth Denham said in a statement: “”I welcome Facebook’s announcement that it will be shutting down its partner category service, using third party data to inform targeted advertising.

“I have been examining this service in the context of my wider investigation into the use of personal data for political purposes and had raised it with Facebook as a significant area of concern. The use of third party sources of data will be covered in more detail in the report my office will publish soon.”

Facebook has for years given advertisers the option of targeting their ads based on data collected by companies such as Acxiom and Experian.

The tool has been widely used among certain categories of advertisers – such as car makers, luxury goods producers and consumer packaged goods companies – who do not sell directly to consumers and have relatively little information about who their customers are, according to Facebook.

The Information Commissioner’s statement came as a House of Commons committee published written evidence provided by a whistleblower who says information about 50 million Facebook users ended up in the hands of political consultancy Cambridge Analytica.

Christopher Wylie, who worked for Cambridge Analytica, alleges that the data was used to help to build profiles on American voters and build support for Donald Trump in the US presidential election.

He also claims that Canadian firm AggregateIQ (AIQ) was involved in the development of the software used to target voters.

Wylie appeared before the Digital, Culture, Media and Sport Committee on Tuesday. The committee said Wylie provided it with documents including a services agreement between AIQ and SCL Elections, Cambridge Analytica’s parent company, dated September 2014.

AIQ has previously said that it did not enter into a contract with Cambridge Analytica and had never been part of the firm. Cambridge Analytica has said it did not share the Facebook profile data with AggregateIQ, did not use it in the campaign to elect Donald Trump, and has deleted the data.