As newspapers worldwide grapple with the challenge of making their content work on mobile phones, the Guardian newspaper is celebrating the successful launch of a paid-for iPhone app.

Introduced in mid-December, the stg£2.39 app has been downloaded more than 100,000 times.

Unlike the Irish Independent’s €2.39 app, which offers only limited content, the Guardian’s app offers access to all stories in the newspaper.

Creator Jonathon Moore, the Guardian’s mobile product manager, insists that the app has extended the paper’s reach. He said it had not cannibalised either the printed paper, the website or even the paper’s mobile browser, which remains free of charge.

This is probably the main concern for newspapers which don’t want relatively low-cost apps to affect their core print business.

‘‘Mobile apps are not instantaneously going to replace anything,” Moore said. ‘‘This is aimed at a very specific audience and it’s not going to be transformative overnight. What it has done is create an interesting new revenue line for us.”

Moore admitted that the Guardian was relatively late to market with its app, but said he felt its delay had been rewarded by its popularity. He said it had taken time to design an app that would, in his words ‘‘delight’’ the audience. Before the iPhone, he noted, it was virtually impossible for any media company to deliver a compelling experience through mobile phones.

Features such as a double-click gallery carousel enable users to browse and enlarge images very quickly and easily.

‘‘We’ve been very ambitious,” he said. ‘‘We created a pay-for application and that’s something that was a risk. It’s not just about charging for content because there’s no content that cannot be reached on our website already.

‘‘So what we’re reaching here is a supplementary mobile audience that’s incredibly engaged. The drop-off rate since launch has been virtually zero.”

Moore would not be drawn on the Guardian’s plans for an app to work on the iPad, Apple’s new ‘‘tablet’’, but said he was monitoring sales of the new gadget.

‘‘As a device, I think it may be a very exciting way for us to continue this journey,” he said. He is working on a range of new apps for different branches of Guardian content, and said he was open to all kinds of commercial options, depending on the product.

The Guardian does not have competition in the app space from the BBC.

In Ireland, RTE already has a series of mobile apps that are delivering news content, offering competition to any new entrant. Moore said he believed all media companies should be thinking about apps, but warned that serious planning was required before launching.

‘‘You have to think very clearly about that you want. I think we’ve proved that a quality product will sell. If you don’t have the resources to create a quality product, then it is going to be more difficult for you. There is capacity to compete more aggressively and commercially in this space, but only with the right product.”

Moore said that growth in the iPhone space was only possible with user recommendations.

‘‘The App Store is littered with failures, and failure is very visible,” he said. ‘‘If you don’t delight people, they will say so. This is a market that rewards excellence.”