Facebook is much better than it was in 2016 at tackling election interference but cannot guarantee the site won't be used to undermine May's European Parliament elections, chief executive Mark Zuckerberg says.
Chastened since suspected Russian operatives used Facebook and other social media to influence a US election that brought Donald Trump to power, Facebook has said it has ploughed resources into safeguarding the EU vote.
Zuckerberg said there had been a lot of important elections since 2016 that have been relatively clean and demonstrated the company's new defences.
"We've certainly made a lot of progress ... But no, I don't think anyone can guarantee in a world where you have nation states that are trying to interfere in elections, there's no single thing we can do and say, okay, we've now solved the issue," Zuckerberg told Ireland's RTE during a trip to Dublin, home to the international headquarters of Facebook.
"This is an ongoing arms race where we're constantly building up our defences and these sophisticated governments are also evolving their tactics."
US intelligence agencies concluded Russia ran a disinformation and hacking operation to undermine the American democratic process and help Republican Trump's 2016 campaign. Moscow denies interfering in the election.
Under pressure from EU regulators to do more to guard against foreign meddling in the bloc's upcoming legislative election, Facebook toughened its rules on political advertising in Europe last week.
It also announced plans to ramp up efforts to fight misinformation ahead of the vote and will partner with German news agency DPA to boost fact-checking.
