SAN FRANCISCO: Pinterest, the social bookmarking website, has announced plans to begin experimenting with paid advertising, opening up the option for businesses to promote certain 'pins' to its 46m users.

The Silicon Valley start-up, which was founded in 2009, will follow a similar model developed at Facebook and Twitter, enabling advertisers to show 'pins' at the top of category feeds and search results.

As an example, the company suggested a search for Halloween ideas might lead users to see a promoted pin from a local or online costume shop, TechCrunch reported.

However, Chief executive Ben Silbermann emphasised that Pinterest would be transparent about paid-for advertising and would work to ensure it learned from user feedback.

He also said the company was determined the site would not host banner or pop-up ads and that any promoted pins would be relevant to its users.

Pinterest is said to be working with a 'select' group of brands to test whether the experiment works and its approach is likely to be cautious to avoid putting off users.

Analytics firm comScore found Pinterest registered 46.9m users in July with 60% of its traffic stemming from the US, 20% from Europe and 10% from Asia Pacific.

Analysts have also noted that its high proportion of female users is likely to attract particular brands and it has a good ratio of referral traffic to purchases.

Rebecca Lieb, an analyst with Altimeter Group, told the Financial Times that the move away from banner or display ads reflected awareness that users frequently ignored them.

She said banner ad prices have been falling "precipitously and steadily" over the years and this is one reason why Pinterest is increasingly positioning itself as an e-commerce venture.

Data sourced from TechCrunch, Financial Times; additional content by Warc staff