A new study by the Office for National Statistics (ONS) has revealed that the number of people connecting to the Internet using a mobile phone has nearly doubled in the past two years.

The study showed that there were 17.6 million mobile phone Internet users in 2011, representing 45% of Internet users, compared to 8.5 million users (23% of all users) in 2009. Of the users, six million people accessed the Internet over their mobile phone for the first time in the previous 12 months.

The rate of growth was fastest among those aged 16 to 24, with Internet use over a mobile phone increasing from 44% to 71% over the previous 12 months.

The number of women using mobile phones to access the Internet has more than doubled, from 18% of Internet users in 2009 to 39% in 2011.

The use of wireless (Wi-Fi) hotspots also increased significantly with 4.9 million people using hotspots at hotels, restaurants, airports etc, compared to 0.7 million people in 2007, found the study.

The use of wireless hotspots almost doubled in the last 12 months to 4.9 million users.

The study also found that 77% of UK households had Internet access.

However, 21% of Internet users did not believe their skills were sufficient to protect their personal data.

Social networking proved to be the most popular activity among 16 to 24 year old Internet users in 2011, with 91% saying they took part in social networking on websites. Around 18% of Internet users aged 65 and over also said that they participated in social networking online.

Overall, social networking was more popular among women, at 60%, than men, at 54%, found the study.

This year, 21% Internet users made telephone or video calls online, and 32 million people (66% of all adults) purchased goods or services over the Internet, an increase from 62% in 2010, found the survey.