Facebook will introduce new measures to boost transparency around adverts in Britain by June and require political ads to be clearly labelled, the firm's chief technology officer has told a British parliamentary committee.
In a written submission to the UK parliament's media committee, Mike Schroepfer said those wanting to run political adverts would have to complete an authorisation process and the messages would also have to display who paid for them.
Facebook has said the personal information of about 87 million users might have been improperly shared with political consultancy Cambridge Analytica, which worked on Donald Trump's 2016 presidential election campaign.
MPs have also raised concern over the use of social media in Britain's referendum decision to leave the European Union in 2016.
"I want to start by echoing our CEO, Mark Zuckerberg: what happened with Cambridge Analytica represents a breach of trust, and we are deeply sorry. We made mistakes and we are taking steps to make sure it doesn't happen again," Mr Schroepfer wrote.
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Earlier this month, Mr Zuckerberg apologised to US senators for issues that have beset Facebook, including shortcomings over data protection.
But the 33-year-old internet mogul managed to deflect any specific promises to support any congressional regulation of the world's largest social media network and other US internet companies.
Mr Schroepfer, who was appearing before the British media committee on Thursday, said it was clear Facebook had not done enough to ensure its tools from "potentially being used for harm" or take a broad enough view of its responsibility.
"That was a mistake," he wrote.
When asked by an MP whether Facebook would apologise for its "bullying" behaviour towards the press, Mr Schroepfer said: "I am sorry that journalists feel that we are trying to prevent them from getting the truth out.
"That is not the intent, so I'm sorry," he added.