Facebook is co-operating with Britain's Information Commissioner's Office as it examines how 30 organisations have used personal data, but the ICO says it's too early to say whether the social media giant has done enough.
On Wednesday, Facebook said the personal information of up to 87 million users, mostly in the US, may have been improperly shared with political consultancy Cambridge Analytica, more than previous estimates.
The ICO said it was looking at how data was collected from a third party app on Facebook and shared with Cambridge Analytica, as well as a broader investigation into how social media platforms have been used in political campaigning.
"Facebook has been co-operating with us and, while I am pleased with the changes they are making, it is too early to say whether they are sufficient under the law," the information commissioner, Elizabeth Denham, said in a statement on Thursday.
"As part of my investigation into the use of personal data and analytics by political campaigns, parties, social media companies and other commercial actors, the ICO is investigating 30 organisations, including Facebook."
Britain's digital and media minister Matt Hancock said he would meet Facebook next week to discuss the scandal. Facebook shares are down over 10 per cent since it first disclosed the leak.
"I expect Facebook to explain why they put the data of over a million of our citizens at risk," Hancock said in a tweet.
"This is completely unacceptable, and they must demonstrate this won't happen again."
It was a sentiment echoed by the European Commission on Thursday, as it sought to meet company officials after revelations more than a million from Europe were among the 87 million users affected.
"For the European Commission, the unauthorised access to and further misuse of personal data belonging to Facebook users is not acceptable," said Christian Wigand, a commission spokesman.
Wigand said that in response to a letter sent by EU Justice Commissioner Vera Jourova last week seeking further information on the issue, Facebook had already reached out and "showed willingness to engage" with the commission.
"Currently, we are in touch to arrange for high-level contacts in the coming days," Wigand said.
Jourova was also set to follow up with European and British data protection authorities investigating the scandal, and additionally with the US Federal Trade Commission, which is looking into the case in the United States.
The "growing scale" of the Facebook data privacy scandal was "very worrying", Jourova wrote on Twitter.
Guy Verhofstadt, an EU MP, reiterated a previous request for Facebook founder and chief executive Mark Zuckerberg to testify before the European parliament.
