Facebook found the passwords of hundreds of millions of users were being stored in a format which could be accessed by employees and took steps to rectify the problem, the latest privacy-related scandal to hit the social media giant.

“As part of a routine security review, we found that some user passwords were being stored in a readable format within our internal data storage systems,” it said in a statement.

“These passwords were never visible to anyone outside of Facebook and we have found no evidence to date that anyone internally abused or improperly accessed them,” it clarified, adding: “We estimate that we will notify hundreds of millions of Facebook Lite users, tens of millions of other Facebook users, and tens of thousands of Instagram users”.

It encouraged users to change their passwords just in case and to consider enabling a security key or two-factor authentication using codes from a third-party authentication app.

The news comes as Facebook CEO Mark Zuckerberg laid out an ambitious plan to rebuild the social media network with a focus on privacy, as regulators in the US and Europe dig in to its data collection practices.

Facebook has been under increased scrutiny since news of the Cambridge Analytica data breach broke in March 2018, with condemnations of its data collection and privacy practices from officials in the UK and Germany.