The country's two largest digital newspapers have been sending more push notifications to mobile readers lately, and not just because of the recent eruption in urgent national news.

The New York Times and the Wall Street Journal -- No. 1 and No. 2, respectively, in terms of U.S. digital circulation, according to the Alliance for Audited Media -- are putting more emphasis on using mobile alerts to distribute breaking news stories and promote their mobile apps.

News publishers have long considered push notifications, which pop up on phone and tablet screens, too intrusive to use more than sparingly. In recent months, however, The Journal and Times have reconsidered that stance and started using them more often.

"We felt comfortable that our breaking news alerts have been well-received by readers and that we may have been a little too stringent about what alerts we should have been sending," said Jonathan Ellis, deputy editor of digital platforms at The Times, which has revised its guidelines on the subject. "More frequently, we're asking ourselves the question 'Should this be a mobile push alert?'"

The change corresponds to in an increase in mobile readership at both newspapers. The Times more than doubled its number of unique visitors on iOS and Android devices over the last year, to 14.3 million in March from some 6 million in March 2012, according to comScore figures encompassing both app users and visitors on the mobile web. The Journal's mobile uniques increased to 4.6 million from from 2.1 million over the same time period.

The Times has also seen its app downloads increase over the past six months. In September 2012, 5.9 million tablet owners (across iOS and Android) and 21.6 million smartphone owners (across iOS, Android, BlackBerry and Windows) had downloaded its app, according to the company. This February, tablet downloads reached a cumulative 7.8 million and smartphone downloads were up to 24.1 million.

The Journal, which declined to provide specific download numbers, said push notifications were helping it serve its audience. "We've seen steep growth in Journal readers accessing content on mobile devices and we've found push alerts to be a very efficient way for us to communicate breaking and markets-moving news quickly," a spokeswoman said by email. The Journal only serves push notifications to iOS app users.

An app download, of course, does not necessarily equate to usage. Push notifications can help apps increase engagement and retain users, according to Brent Hieggelke, CMO at Urban Airship, a company that provides push notification technology for app publishers. People who opt in to an app's push notifications open that app five times more often than those who don't receive push notifications, and they are twice as likely to keep that app on their device, he said.

But there is still such a thing as too many alerts, Mr. Hieggelke cautioned. "Push is not a channel to nag your customer," he said. "That's a terrible experience."

The Times, still wary of overdoing it, plans to be judicious in selecting which breaking stories warrant a push notification, Mr. Ellis said.

Both The Journal and Times sent numerous push notifications about developments in the Boston Marathon bombings story and the subsequent manhunt. But as that event proved, racing to be the first can have dire consequences. Many news organizations were quick to relay information later found to be inaccurate.

Still, The Journal and The Times will be sending more push notes than in the past. The Times pointed to two stories from February -- headlined "Birth Control Rule Altered to Allay Religious Objections" and "American and US Airways Announce Deal for $11 Billion Merger" -- as examples of stories that would justify push notifications under its revised guidelines.

"Push in general has become an important field, like email was," said Lars Albright, CEO and co-founder at Session M, a platform that helps app publishers generate revenue and retain users with rewards. "The consumer is more used to getting this kind of messaging."

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CORRECTION: An earlier version of this story incorrectly identified the Alliance for Audited Media as the Audit Bureau of Circulations. The organization changed its name last November.