A scathing British parliamentary report on Monday branded Facebook "digital gangsters" who failed to fight the spread of fake news and violated data privacy.
Lawmakers' 18-month investigation into technology companies and disinformation also accused the world's largest social media platform of trying to hide the extent of Russian interference in foreign elections.
Facebook is coming under attack over its response to Russia's suspected use of misleading stories and targeted ads to sway the 2016 US presidential election and a series of European votes.
Its executives have further been accused of trying to either hide or suppress emerging evidence of foreign meddling flagged by its engineers.
Parliamentary committee chair Damian Collins said Facebook "deliberately sought to frustrate our work by giving incomplete, disingenuous and at times misleading answers to our questions".
Facebook co-founder and chief Mark Zuckerberg turned down three requests to appear before the committee.
"Companies like Facebook should not be allowed to behave like 'digital gangsters' in the online world, considering themselves to be ahead of and beyond the law," the 108-page report said.
Liable for content
The committee urged a compulsory code of ethics for all tech companies that would be overseen by an independent UK regulator.
Collins told AFP he hoped "that before the end of the year, there could be a firm proposal for legislation" establishing how such an oversight body would work.
"This ends the idea that tech companies are just platforms, that they are independent and that the responsibility for the content lies solely on the person who posted it," Collins said in a phone interview.
"They have limited liability for the content that has been posted there. They are not neutral. They curate the space, they promote content toward users."
Facebook spokesman Karim Palant said executives at the California-based company "share the committee's concerns about false news and election integrity."
"We are open to meaningful regulation and support the committee's recommendation for electoral law reform," Palant said in a statement.
But Collins said Facebook has only adopted incremental policy changes that were mostly aimed at fending off regulation making it liable for the spread of malicious stories.
"They have taken a step, largely I think, to offset legislation," said Collins.
"It shouldn't be down to Mark Zuckerberg to determine what the code is for election advertising in the UK through Facebook."
'No longer good enough'
The committee earlier found that Facebook's engineers had flagged potentially malicious Russian activity as early as 2014 - long before it became public.
Monday's report said the two Facebook officials who did testify "deliberately misled the committee or they were deliberately not briefed by senior executives at Facebook about the extent of Russian interference in foreign elections".
UK officials have been probing the role Russian misinformation campaigns may have played in swaying Britons toward voting in favour of leaving the European Union in 2016.
Russia has denied either backing Britain's decision or covertly backing pro-Brexit leaders during the divisive campaign.
The committee further accused Facebook of offering Netflix and other popular apps preferential access to people's data even after it had tightened its privacy rules.
"They are acting in an aggressive way against other companies that could be considered a commercial threat to Facebook," Collins told AFP.
The British government has eight weeks to respond to the parliamentary report.
Britain is coming under pressure to follow the example set by Germany and France of introducing rules governing how Facebook collects user data and fights fake news.
And France has introduced laws requiring social media giants to take down malicious stories during election campaigns.
Collins said it would be up to parliament to determine what rules and punishments to impose.
"We feel that it's no longer good enough just to ask the tech companies to get better," he said.