The decision may reflect the increasing importance that Facebook sees in Web search technology, a market dominated by rival Google.
Searches on Facebook have long been geared towards helping users connect with friends and to find other information that exists within the walls of the 1.35 billion-user social networking service. But for years, Facebook's search results also included links to standalone websites that were provided by Bing.
"We're not currently showing web search results in Facebook Search because we're focused on helping people find what's been shared with them on Facebook," a company spokesperson told Reuters. "We continue to have a great partnership with Microsoft in lots of different areas."
Microsoft was not immediately available for comment.
Facebook Chief Executive Mark Zuckerberg has flagged search as one of the company's key growth initiatives, noting in July that there were more than 1 billion search queries occurring on Facebook every day and hinting that the vast amount of information that users share within Facebook could eventually replace the need to search the Web for answers to certain questions.
"There is more than a trillion posts, which some of the search engineers on the team like to remind me, is bigger than any Web search corpus out there," Zuckerberg said on a conference call with analysts in July.
Microsoft's Bing is the No 2 Web search provider in the US, with a nearly 20 per cent share of the market according to industry research firm comScore.
Facebook and Microsoft have a longstanding relationship dating back to Microsoft's $240 million investment in Facebook, for a 1.6 per cent stake in the company, in October 2007. As part of that deal,
Microsoft provided banner ads on Facebook's website in international markets.
Facebook stopped using Microsoft banner ads in 2010 as it moved to take more control of its advertising business. But Facebook, during that same time, expanded its use of Microsoft Bing search results to international versions of its service.