The House of Commons has cut its links to the websites of all 334 outgoing members of Parliament after it discovered the sites of some MPs were being used to campaign for re-election.

Heather Bradley, spokesman for the House of Commons, said Clerk Charles Robert sent a memo to all MPs late Thursday informing them that the House website no longer links to their MP sites. Although the sites themselves still exist, they can no longer be accessed via the House site.

"Upon reviewing sites, many were using them for not the right purpose," Bradley said. "It's just an easier way to manage it."

Under Parliament's rules, MPs are not allowed to use House of Commons resources for election campaigns.

Bradley did not say which MPs were not using their sites for the right purpose.

Move breaks with the past

The decision to cut the links to the websites appears to be a break with past practice. During the 2015 election campaign, links to MPs' websites remained on the House of Commons site, according to an archival version of Parliament's website.

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

The websites attached to the profiles of three NDP MPs — Charlie Angus, Don Davies and Scott Duvall — still linked to a regular MP website.

A few days ago, NDP MP Niki Ashton's website on the House of Commons page linked to her MP site. Wednesday, the link automatically redirected to a re-election campaign site.

The party controls the websites of many of its MPs.

NDP spokesperson Mélanie Richer said the NDP changed to campaign websites once the campaign began in order to comply with Elections Canada regulations.

Investigation found trackers

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

That means that people who visit those websites looking for information — to renew their passports, for example, or to contact their MPs — could find re-election ads for that MP popping up in their Facebook feeds or on websites they later visit.

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, New Democrat MPs had the highest number of trackers and Liberals had the lowest. Conservative MPs varied widely.

New Democrats Angus, Davies and Duvall had fewer trackers attached to their websites than many of their colleagues.

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.

Advertising trackers are not illegal, and they are used by many websites, including CBC pages.

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

Parliament's governing body, the Board of Internal Economy, acknowledged in May that there were gaps in the rules governing MP sites. It plans to look at the issue when the next Parliament begins sitting.

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