By Alexei Oreskovic SAN FRANCISCO (Reuters) – Facebook Inc is testing a new buy button on its website that will let consumers purchase products that are advertised on its social network. The new service, which Facebook described on Thursday as a test with a few small and medium-sized businesses in the United States, represents the Internet social networking companys latest effort to play a bigger role in the e-commerce business. Facebook said its new Buy button will be available on the mobile and desktop PC version of its website and will allow consumers to purchase goods directly from participating businesses. None of the credit or debit card information people share with Facebook when completing a transaction will be shared with other advertisers, and people can select whether or not they’d like to save payment information for future purchases, the company said in a blog post on Thursday.