Yahoo Japan replaced a Sony-affiliated music download service with Apple's iTunes Store on Thursday as the default music store on Yahoo Music Japan.

The partnership means that visitors to the Yahoo Music pages now see a prominent link to iTunes in the menu bar and one-click access to the download service. Until Thursday, Yahoo Japan had relied solely on Mora, a download service run by the Sony-affiliated LabelGate, for music downloads. Financial details of the deal were not disclosed.

Access to Mora is still available through Yahoo Japan although users must log-in to the site and make it their preferred music store. The iTunes link appears by default.

The change is likely to be good news for Apple as Yahoo Japan is far and away the most popular portal site in the country. It reaches around 40 million people, or 84 per cent of the country's internet users accessing the web from home each month, according to NetRatings Japan.

The collaboration between Yahoo and Apple might come as a surprise to some as the two companies battle each other in the US market. But the Japanese deal doesn't necessarily fortell similar alliances in other markets.

Yahoo Japan is a listed company, with Softbank its largest shareholder. Softbank helped provide early venture financing for Yahoo in the US.

Yahoo follows as the number two shareholder with a roughly one-third stake. The result is that Yahoo Japan's business is fairly independent of the US.