Opera's Web browser for mobile devices, Opera Mini, has been used to view over one billion page views since it was launched seven months ago.
On Tuesday, the company said that the most popular sites for its five million users are Google search, community and dating sites, and email.
"This proves there is a need for free, easy-to-use, mobile Web browsers," said Eskil Sivertsen, public relations manager for Opera Mobile. "It shows that people don't want expensive WAP content or to be limited in walled gardens, which will be an eye-opener for the mobile industry," Sivertsen added.
Opera Mini takes standard HTML Web pages and processes them into a simpler form so they can be viewed more easily on a small screen.
Domains for adult entertainment were also popular choices for mobile Web browsing.
"We note with interest that some people use it to browse porn. That's interesting because the phones have tiny screens, not big screens like computers," said Sivertsen.
Opera collated the information on browsing habits through its Opera Mini server, which pre-processes all browser queries before the information is sent to the user.
The most popular site accessed in the UK was BBC News, followed by eBay, Google, and MySpace.
However, according to a recent survey, consumers are still reluctant to use mobile devices to access the Web.
The survey of 1,484 consumers was conducted on behalf of Web-hosting company Hostway by TNS. It found that 73 percent of people did not access the Internet using mobile devices. Slow download speeds, difficult site navigation and the unavailability of some Web pages were all cited as negative factors.
"At the moment, most Web sites just aren't flexible enough to be accessed on mobile phones," said Neil Barton, director of Hostway.
"There's nothing wrong with having a flash Web site with all the bells and whistles you can muster, but you've got to be aware that mobile users simply aren't going to be able to access it. The research illustrates that even if people do wait for sites to load, quite often it's impossible to actually get at the content itself because of the way that sites are built."
Opera agreed, and called on Web developers to make Web pages easier to render on a small screen, while adding that its own small-screen rendering process worked "quickly".
"The perfect solution is if developers made Web pages mobile friendly. Until then we have small-screen rendering," said Sivertsen. "We have worked hard to render Web pages quickly."
Sivertsen said that slow download speeds could be caused by mobile operators using the WAP protocol for Web services.
"Operators have been selling WAP as mobile Internet for a long time. Often you have to pay for the content, it's slow, and the user experience is not good," said Sivertsen.
"A lot of operators in Europe, if they have WAP services, are scared they will lose revenue if they give people full access to the Internet. But with that amount of traffic, it's revenue in their pocket in terms of data plans," Sivertsen added.
Opera also said that mobile Internet access could "bridge the digital divide" by giving full Internet access to people in the world who cannot afford a PC.
DotMobi is driving the creation of a top-level domain for Web pages, .mobi, designed specifically to be viewed on mobile phones. The company is partly sponsored by Microsoft, Ericsson, Nokia and Vodafone, and argues that mobile Web access had an "air of inevitability".
"Mobile Web will be the new mass media," said Ronan Cremin, director of development initiatives for DotMobi. "There's a huge degree of inevitability. Pretty much everyone throughout the world who has a job can afford a phone," Cremin told ZDNet UK.