The House of Commons will review all MP websites after an investigation by CBC News revealed that dozens of them have trackers that can be used to target advertising to people who have visited the sites.

Heather Bradley, spokeswoman for the House of Commons, said there are no rules specifically about trackers, but MPs cannot use the websites linked to by the House of Commons to get themselves re-elected.

"The governing policy for MP websites does not cover the use of trackers," Bradley wrote in an email. "MP websites linked from the House of Commons members' information page cannot be used for campaign purposes.

"Following the dissolution of the of the 42nd Parliament, the administration is reviewing all of these websites for policy compliance and will follow up with MPs directly as required."

While most MPs had some sort of tracker attached to their websites, including trackers that provide site analytics, at least 99 had one or more trackers used to target advertising.

While there were exceptions in each party, in general NDP members had the highest number of trackers and Liberals had the lowest. Conservative MPs varied widely.

A review by CBC News late Wednesday afternoon found that 87 percent of the websites for NDP MPs now automatically redirect to the NDP.ca campaign site or to MP re-election campaign sites with donation buttons.

A few days ago Niki Ashton's website on the House of Commons page linked to her MP site. On Wednesday it redirected to a re-election campaign site. Now, the House of Commons has cut links to MP sites.

The websites attached to the profiles of only three New Democrat MPs — Charlie Angus, Don Davies and Scott Duvall — still link to a regular MP website. During the CBC News investigation, those three MPs also had fewer trackers attached to their websites than many of their colleagues.

Two websites — for MPs Pierre-Luc Dusseault and Gord Johns — would not load.

Many of the NDP MP websites are controlled by the party, spokeswoman Melanie Richer told CBC News earlier this week.

"Most MP pages are run by us, but a few are run by the MP's team."

The review by the House of Commons comes after the CBC News investigation revealed that dozens of MPs have advertising trackers embedded on their websites which could allow them to target visitors to their sites during the election campaign.

That means that people who visit the sites to find out how to renew a passport or contact an MP could find re-election ads for that MP popping up in their Facebook feeds or on websites they later visit.

The use of trackers on MPs websites also raises privacy questions, particularly in the wake of the Cambridge Analytica scandal, which demonstrated how political advertising can be microtargeted toward individual voters using their online profiles. Experts say MPs also may not be aware of how much information the trackers allow tech companies to gather about visitors to their websites.

In the wake of the investigation by CBC News, privacy and democracy watchdogs are calling for the next Parliament to change the law to subject federal political parties to privacy laws and to clear up grey zones like the use of advertising trackers on MP's websites.

The Canadian Civil Liberties Association took aim at the practice in a tweet.

"The dirty little secret tracker on your MP's website: misusing parliamentary technology to get re-elected; misusing the power of incumbency to unfair advantage," the association wrote.

"It's time for Canada to end political party immunity from privacy laws."

Website trackers are not illegal and are used by many websites; cbc.ca and many other media websites use them for analytics and advertising.

Duff Conacher, co-founder of Democracy Watch, said Canadians should have to consent to the use of trackers when they visit an MP's website.

"The big problem is that voters are not consenting to their personal information being collected and being shared, not only with the MPs and likely their parties, but also with social media companies that would be placing ads in their news feeds and when they're searching on the internet."

Nearly a third of MPs have trackers embedded on their official websites that could allow them to target visitors with campaign ads, an investigation by CBC News reveals. 1:56

"It's an invasion of privacy to be collecting this information without voters' consent and it shouldn't be allowed without voters' explicit consent."

Conacher said the problem is that political parties are currently exempt from federal privacy laws — something the next Parliament should change.

"The Liberals refused to make that change, so it is now left to whoever forms the next government and all the parties together to finally close this gap that allows parties and MPs to invade the public's privacy."

Elizabeth Thompson can be reached at elizabeth.thompson@cbc.ca