Readers of the National Post and a slate of other Canadian newspapers owned by the same company are being asked to start paying for content.

The Post, as well as the Ottawa Citizen, Vancouver Province and Vancouver Sun — all owned by Postmedia — have established "pay meters" that limit the number of stories that can be read before users are asked to buy a subscription.

The move, which was to come into effect by the end of Tuesday, is part of a plan to drive revenues to help counter lower advertising and print circulation income.

Each of the local papers will charge 99 cents for a 30-day trial period for unlimited access to the website and iPad application. After that, the price will rise to $7.95 per month or $79.50 per year for the Sun or the Province. The Citizen will charge $9.95 per month or $99.50 per year.

Print subscribers already have the digital subscription as part of their package.

Users who don't pay for the subscription will still have access to breaking news stories for free, as well as 15 other articles per month.

At the Post, fees will only apply to international readers, a move that will also ensure that Canadians who regularly travel outside the country will also need to subscribe.

A similar model will be in place at Postmedia's Montreal Gazette, which has already had a metered wall in effect since last year.

Postmedia Network Inc. is following a business model that is growing in popularity, particularly in the United States.

The New York Times launched a metered service earlier this year, while McClatchy Co., one of the largest U.S. newspaper groups, announced last month it would do the same.

In Canada, the Globe and Mail has said it also plans to introduce a metered business model later this year.