Facebook has announced that data on 87 million users was improperly shared with a British political consultancy firm.

The social media giant is under investigation by authorities in the US, UK, and EU over claims its policies allowed political consultants Cambridge Analytica to harvest data from millions of users.

The figure announced this evening is a significant rise on the 50 million users the company had originally admitted were affected.

Announcing the updated figure, Facebook said most of those affected were in the US – and launched new privacy tools to protect users' data.

Over one million users in the UK were also affected.

Newstalk’s tech correspondent Jess Kelly says the changes were inevitable:

“It was only a matter of time before Facebook took action in the wake of Cambridge Analytica,” she said.

“The social media giant is saying that it is thought that around 87 million people were impacted by the Cambridge Analytica story – so it makes sense that they are making these changes.

“As part of this process, Facebook will also tell people if their information may have been improperly shared with Cambridge Analytica.”

Facebook this evening announced nine “important changes” to its data protection policies, adding that it will keep the world “updated on our progress.”

“Overall, we believe these changes will better protect people’s information while still enabling developers to create useful experiences,” said the company statement.

“We know we have more work to do — and we will keep you updated as we make more changes.”

Cambridge Analytica has worked with political groups all around the world – including US President Donald Trump’s election campaign.

The harvested data was allegedly used to create user profiles in an effort to target political advertisements and influence voters.

This afternoon, the US House Energy and Commerce Committee announced that Facebook founder Mark Zuckerberg had agreed to appear before it next week to answer questions.