Stock index futures were lower on Tuesday after cautious comments from Federal Reserve Chairman Ben Bernanke sparked jitters about the pace of economic recovery.

Speaking at the Economic Club of Washington on Monday, Bernanke said inflation could remain subdued, but the U.S. unemployment rate could remain elevated, for some time.

Bernanke said the U.S. economy faces formidable headwinds, including a weak labor market and tight credit conditions that have persisted despite the Fed's efforts to support the economy.

FedEx Corp will be in the spotlight after it said late on Monday its second-quarter earnings would easily beat its previous forecast, citing strong growth in international demand for its air services, especially in Asia and Latin America.

Research In Motion will be a focus after it said it and China Mobile <0941.HK> will offer Blackberry handsets and Internet service to consumers as well as smaller firms in China.

General Motors Co is talking to BAIC, China's fifth-largest car maker, about a partial sale of assets associated with its Saab brand, including tooling and technology, two people with direct knowledge of the discussions said.

Six months is not enough time to restructure indebted, state-controlled conglomerate Dubai World, the emirate's finance chief said, adding it had enough assets to meet its obligations.

S&P 500 futures fell 6.6 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures slipped 60 points, while Nasdaq 100 futures dipped 13.75 points.

The S&P 500 and Nasdaq ended slightly lower on Monday and the Dow was flat, reversing earlier gains following Bernanke's comments.

(Reporting by Leah Schnurr; Editing by Padraic Cassidy)