BRUSSELS - Facebook boss Mark Zuckerberg apologised to European Union lawmakers on Tuesday for a massive data leak, in his latest attempt to draw a line under a scandal that has rocked the world's biggest social media network.

Zuckerberg agreed to meet leaders of the European Parliament to answer questions about how political consultancy Cambridge Analytica improperly got hold of the personal data of 87 million Facebook users, including up to 2.7 million in the EU.

In his opening remarks, Zuckerberg said it had "become clear over the last couple of years that we haven't done enough to prevent the tools we've built from being used for harm as well."

"Whether it's fake news, foreign interference in elections or developers misusing people's information, we didn't take abroad enough view of our responsibilities. That was a mistake,and I'm sorry."

His comments, sitting at a circular table with EU Parliament leaders, dressed in a suit, tie and white shirt, echo an apology last month to US lawmakers.

But questions remain over how Facebook let the leak happen and whether it is doing enough to prevent a recurrence.

Zuckerberg's appearance in Brussels comes three days before tough new EU rules on data protection take effect. Companies will be subject to fines of up to 4 percent of global turnover for breaching them.

In the session, Manfred Weber, leader of the centre-right in the European Parliament and an ally of German Chancellor Angela Merkel, asked Zuckerberg why Facebook shouldn't be broken up as a monopoly.

Zuckerberg declined to answer specific questions on the cross-use of data from Facebook, its WhatsApp messaging service which has more than one billion daily users, and the blocking of target ads. As he did with a series of questions from US lawmakers last month, Zuckerberg said he would send follow-up answers later.

However, he said Facebook expected to be compliant with the EU rules, called the General Data Protection Regulation, when they come into force on May 25, stressing the company's commitment to Europe where it will employ 10,000 people by the end of the year.

"I believe deeply in what we're doing. And when we address these challenges, I know we'll look back and view helping people connect and giving more people a voice as a positive force herein Europe and around the world," he said.

Reuters