OTTAWA - A recent ruling that changes how the country's largest Internet service providers charge their customers is raising hackles in the online community amid fear it could lead to higher bills for heavy users.

Joining that chorus of concern Tuesday was none other than Prime Minister Stephen Harper -- on Twitter, no less.

As Internet use soars, the burgeoning popularity of downloading -- a huge number of games, music and movies are available over the Internet these days -- brings with it the concern that Canadians might be far heavier users than they realize.

Critics say the ruling by the Canadian Radio-television and Telecommunications Commission will lead to lower download limits and higher rates as those who exceed their pre-set limits are charged for additional bandwidth.

They're not the only ones worried about the move. Harper ((at)pmharper) used the popular social-networking site Twitter to echo the concerns expressed earlier by Industry Minister Tony Clement.

"We're very concerned about CRTC's decision on usage-based billing and its impact on consumers," Harper tweeted.

"I've asked for a review of the decision."

The ruling affects the wholesale business of the major Internet service providers, who sell capacity to smaller resellers who may be forced to charge their users more or reduce download limits.

In Ottawa, National Capital Freenet's users can currently use up to 200 GB per month as part of their monthly DSL service, which the non-profit organziation buys in bulk from Bell.

The rule changes, the organization says, will likely force it to introduce new usage-billing thresholds at 60 GB and 300 GB.

"This will add to NCF members' administrative costs, and will be a hassle and expense for everyone," the group said in a message on its website.

Lindsey Pinto of telecommunications advocacy group OpenMedia.ca said those small resellers hold the larger providers in check by providing competition.

"These independent service providers are no longer really available to provide that check because they have to pay based on what their customers are using directly to the incumbents that they purchase wholesale from," Pinto said.

As users stream more and more data into their homes, including movies, music, television shows and software, usage caps can quickly be exceeded.

While downloading files or streaming radio over the Internet is not new, streaming video -- especially high-definition video -- uses exponentially more capacity that listening to a favourite faraway radio station online.

Both the opposition Liberals and the NDP have come out against the CRTC ruling.

New Democrat digital affairs critic Charlie Angus, who has long campaigned against usage-based billing for Internet service, called it a ripoff.

"The problem with this announcement that he's made is it refers to the decision by the CRTC which was allowing the large ISPs to squeeze out the minimal amount of competition in the country," Angus said of the prime minister's tweet.

"We're saying: What about every Canadian who's getting ripped off month after month? So if the caps are coming off ISP competition, take the caps off every family, off every business, off every consumer because we are being ripped off at an extraordinary rate.

An online campaign against usage-based billing by OpenMedia.ca has bombarded Clement with thousands of messages through email and Twitter.

The group's online petition has received more than 200,000 signatures asking the minister to overturn the ruling. A hashtag for discussing usage-based billing -- .ubb -- was a trending topic on Twitter on Tuesday.

Clement suggested the review would take a matter of days with the new rules are set take affect on March 1.

"We're concerned about how it impacts on consumers, on small business operators, on entrepreneurs, on creators, all Canadians," he said after question period in the House of Commons.

"And we as a government have been focused on making life easier for our small businesspeople, for our creators, for consumers generally."

The major Internet service providers have argued that usage-based billing is fair because it means heavy users pay more than those who just use email and do a little web surfing.

Bell (TSX:BCE) said as it invests billions in new broadband capacity, pricing structures from the 1990s need to be brought in line with the extraordinary growth in Internet usage.

Rogers (TSX:RCI.B) noted that its customers are using about 40 per cent more data each year.

"To keep up with the demand, we have two choices -- control traffic or spend money on upgrades," Rogers spokeswoman Kathy Murphy wrote in an email.

"We put data allowances in place several years ago to limit extremely high use of data by a small number of customers so that the rest of our customers aren't slowed down. Those who use more data pay more."

Watching content through video-streaming service Netflix can typically eat through between one or two gigabytes an hour, depending on the quality of the video.

Some lower-end high speed accounts offered by Canada's large ISPs include only 25 GB of downloading a month, the equivalent of about 12 hours of Netflix viewing in high definition, with additional usage charges that can be as much as $5 per GB for the cheapest plan, depending on the provider.

At the top end, Rogers's "Ultimate Internet" service, which costs $99.99 a month, offers 175 GB per month in Ontario, while Bell's "Fibe 25" service offers 75 GB for $67.95 a month.

Netflix chief executive Reed Hastings recently said the download caps set by Canadian service providers could be "a significant negative" for his company.

U.S. Internet giant Comcast caps data usage at 250 GB.

The Liberals say the CRTC decision will ultimately lead to higher Internet rates for all.

"It's clear that consumers and business have not had a lot of input in this and what input has obviously been given reduces affordability, it reduces choice and reduces access," Liberal consumer affairs critic Dan McTeague said.

"We are moving very rapidly towards a digital age in which options and choice for consumers are there and we have the CRTC which has decided to basically stymie that in favour of those who control bandwidth."