OTTAWA -- The federal privacy watchdog is calling on the government to address what he calls significant gaps in the law that allow political parties themselves to police how they gather and use voter data.

Political parties are only bound by internal, voluntary privacy policies in the absence of an independent body to ensure they follow their own rules, federal privacy commissioner Daniel Therrien told a parliamentary committee Tuesday.

Therrien has been calling for changes to strengthen privacy laws to cover how political parties use data -- a campaign that has been attracting fresh attention in recent weeks following revelations about how Facebook and other companies treat the personal data of its users.

"Neither I nor any other independent person can verify what's going on," said Therrien, who reasserted his demand for stronger privacy laws as he appeared before MPs in Ottawa.

"If there was ever a time for action, I think frankly, this is it."

His testimony comes as policy-makers and regulators around the world examine how to better protect the online data of users as allegations swirl that tens of millions of Facebook users had their personal information improperly accessed for political purposes.

Facebook estimates the personal data of 622,161 users in Canada -- and nearly 87 million worldwide -- was inappropriately harvested by firms that allegedly used the information to help deliver electoral wins in the U.K.'s Brexit referendum and the 2016 U.S. presidential campaign.

Therrien's office recently joined forces with British Columbia's privacy commissioner to investigate Facebook and Canadian company AggregateIQ Data Services Ltd. -- two firms at the centre of the global uproar over the unauthorized use of social-media data.

The privacy controversy has ramped up scrutiny of the use of data by political parties, which rely on access to quality information about voters in order to target and fine-tune their campaign pitches.

The parliamentary committee on access to information, privacy and ethics is holding hearings this week on the data breach involving Facebook and Cambridge Analytica.

On Thursday, the committee will hear from Kevin Chan, Facebook Canada's head of public policy. Chan is a former policy director for former Liberal leader Michael Ignatieff.

Facebook Canada reached out to committee members Monday in preparation for the appearance by Chan, who will be questioned by MPs from all parties, to offer them a briefing "on the Cambridge Analytica situation."

"Should this be of interest, please let us know and we will work with your office to schedule a briefing on either April 16, 17 or 18," Jessica Smith, a public policy associate for Facebook Canada, wrote in an email to NDP MP Charlie Angus.

The NDP shared the email with The Canadian Press, describing such invitations as "rare."

In his testimony Tuesday, Therrien pointed to the U.K., much of the European Union and New Zealand as jurisdictions with laws that apply to political organizations.

In Canada, it's high time an independent authority was given the powers to monitor the practices of political parties and determine whether they are truly protecting privacy rights, he argued.

As an example, he noted, federal parties lack policies that would allow electors to find out more about the personal information that is in political hands.

"That's a huge flaw," said Therrien.

The issues overlap both privacy concerns and how the information is used for political purposes, he added. Both his office and the chief electoral officer could contribute to monitoring political parties, he suggested.

When it comes to legislating the use of data, Therrien acknowledged it's important to find a balance between enhancing the rules of consent around the collection of personal information and considering areas, such as health care, where gathering information is a benefit for society.

Therrien said his investigation, which includes collaboration with the U.K. privacy commissioner, is "somewhat complex," but he hopes to conclude it within a year.

AggregateIQ, a Victoria-based data-analysis company, is also under investigation by privacy officials in the U.K. for its role in influencing the outcome of the Brexit referendum. It is also under investigation for allegedly violating limits on spending during that campaign to benefit the "leave" side.

The firms has also been linked to Cambridge Analytica, the political consultancy firm accused of improperly accessing private Facebook data to help political campaigns, including Donald Trump's U.S. presidential bid and Brexit.

Facebook recently suspended AggregateIQ from its platform following reports that the company may be connected to Cambridge Analytica's parent company, SCL.

AggregateIQ has said it has always complied with the law and has denied ever being part of Cambridge Analytica or SCL. It has also said it never entered into a contract with Cambridge Analytica, nor has it ever had access to Facebook data allegedly obtained improperly by Cambridge Analytica.