Nine million US mobile phone subscribers have used their handsets to pay for goods or services, according to data released today.

Nielsen Mobile's monthly Mobile Insights survey of more than 30,000 US wireless subscribers found that half of all data users expect to participate in mobile commerce in the future.

Men were more likely than women to use their phone for commerce: 4.5 per cent of men (4.9 million) and three per cent of women (4.3 million) indicated that they have made a purchase using their phone.

Adults aged 25 to 34 are the most likely to have made a purchase using their phone: 5.4 per cent of adults in this category (three million) have made a purchase, compared to 3.6 per cent of all mobile subscribers.

The research indicates that mobile websites are one popular way that consumers make purchases over the mobile phone.

Of the 40 million active US users of the mobile web in April 2008, five million accessed mobile shopping and auction websites, up 73 per cent from April 2007 when just 2.9 million mobile users did so.

Auction site eBay.com is the most popular shopping or auction destination on the mobile web with 3.4 million unique visitors in April.

Purchasing items via text message is another growing form of mobile commerce. Some services allow consumers to send text messages to a phone number in order to be charged for goods or services directly on their mobile phone bills.

Already, 6.5 million US mobile consumers say they have used text messaging to purchase an item.

"For many of the millions of consumers who are already shopping online or over landline phones, mobile commerce is an obvious and useful extension," said Nic Covey, director of insights at Nielsen Mobile.

"As more mobile commerce services become available, and consumers develop a greater trust for phone-based transactions, we expect commerce to be an increasingly important part of the mobile experience next year and beyond."