The federal and British Columbia privacy commissioners are joining forces to investigate Facebook and Canadian political consultancy AggregateIQ — two firms at the centre of an international uproar over the unauthorized use of social-media data.

The controversy involves allegations of the improper use of private Facebook information to help support major political wins, including Donald Trump's 2016 U.S. presidential campaign.

The federal privacy watchdog launched an investigation last month to look into allegations about the unauthorized access of private Facebook data.

It is now broadening its investigation by joining the B.C. privacy czar's probe of Victoria-based firm AggregateIQ, which began late last year, to determine whether the company broke privacy laws.

Facebook estimates 622,161 users in Canada had their data improperly shared with another political consultancy firm Cambridge Analytica, which is linked to AggregateIQ.

Privacy commissioners in B.C., and the United Kingdom had previously opened investigations into AggregateIQ over its alleged role in the 2016 Brexit campaign, which resulted in Britain's vote in favour of leaving the European Union.