"Facebook has long called for reform of the global tax rules and we welcome the important progress made at the G7," Clegg said on Twitter. "Today's agreement is a significant first step towards certainty for businesses and strengthening public confidence in the global tax system.

"We want the international tax reform process to succeed and recognize this could mean Facebook paying more tax, and in different places."

(Reporting by Kate Holton; editing by Michael Holden)