Apple's iTunes Music Store has taken on peer-to-peer file sharing sites where music can be illegally downloaded for free, and won, almost.

iTunes proved more popular than P2P services Kazaa and BearShare, and tied for second place with LimeWire, according to data from market research firm NPD Group.

The most popular Web destination for downloading music was WinMX, although iTunes was only "slightly" behind, according to the research. The data showed that 1.7 million US households had download at least one track from WinMX in March.

Napster ranked in seventh place, the Real Player store was number nine.

NPD Music and Movies division president Russ Crupnick told Reuters: "One of the music industry's questions has been when will paid download stores compete head-to-head with free P2P download services. That question has now been answered. iTunes is more popular than nearly any P2P service, and two other paid digital music offerings have also gained a level of critical mass."

The average consumer buying music online was 33 years old and four per cent of Internet-enabled US households used a legal online music store in March, according to the NPD research.