Facebook plans to escalate its use of personal data to target advertisements to individual users, despite mounting privacy concerns surrounding social networking sites.

Owen Van Natta, the company’s chief revenue officer, told The Times that Facebook would add new advertising features in coming weeks in a bid to boost revenue. Facebook regards making adverts more personal as a priority, he said.

Chris Kelly, the chief privacy officer, added: “We have always said that information [submitted by users] may be used to target adverts.”

Making online advertising as targeted as possible has become the holy grail of e-commerce, with groups such as Google insisting that they “do not yet know enough” about their users to realise their commmercial potential. Amid efforts to glean more about individuals’ online habits, however, privacy is proving an increasingly contentious issue.

Mr Kelly said yesterday that the group was “very comfortable” about its position on a range of legal issues – including privacy protection, copyright and the prospect of being drawn into libel cases should users post defamatory comments on the website. He suggested that internet-users could no longer expect to remain anonymous online, but could control only the amount of information about them that is available on the web.

Asked about last week’s decision by Facebook to make basic details, including names and photographs, of its users accessible through search engines including Google for the first time, Mr Kelly said that the result would be the internet equivalent of a telephone directory listing and represented no threat to privacy.

Keith Reed, of Trend Micro, the internet security group, said: “The concern is the ease with which criminals can find information on the individual which can be used for ID theft.”

Facebook users would be accessible through a search engine only if they did not opt out of the system, Mr Kelly said. One in five Facebook users had altered their privacy settings to reduce their visability, he added.

According to Mr Kelly, Facebook compares favourably with alternative websites, such as blogs, where information is “completely discoverable”.

The comments came as senior Facebook executives gave an insight into the privately owned company’s long-term thinking. In particular, the group is showcasing its investment in what it calls the “Social Graph” - a vast database of its users’ social and professional relationships. The information is being refined to make it more commercially valuable. Facebook suggested that the project is key in its plans to evolve from an online talking shop to a “massive distributive network” for services and advertising. The Graph project is at the root of its efforts to leverage the vast amounts of social and demographic information its users entrust to it. Chamath Palihapitiya, vice-president for product marketing and operations, said that “being able to abstract . . . the Social Graph” was key in setting Facebook apart from a host of rival social networking companies.

Facebook also revealed that it had secured an office in Soho to expand its operations in Britain, its fastest-growing market.

The Facebook site is considered a potential goldmine for advertisers because of the amount of data that it gathers, ranging from favourite music tracks to details of life events such as birthdays and engagements. Its success in reaping revenues, however, is thought to have been limited – a key concern for a group that has suggested that it could float for as much as $10 billion within two years.

The site, which began three years ago, claims 40 million active users. “We are adding 200,000 more every day,” Mr Van Natta said. It declined to detail its financial performance, but analysts have suggested that Facebook will post a $30 million (£15 million) profit this year on revenues of $150 million – levels considered poor, given its online reach.