File picture: Chip East, Reuters

New York - US stocks index futures were slightly lower on Tuesday as investors await Federal Reserve Chair Janet Yellen's speech for clues about when the central bank may raise interest rates.

Yellen, who is due to speak before the Economic Club of New York at 12:20 p.m. ET (1620 GMT), will make her first remarks since the Fed's meeting in March.

The central bank has said it will depend on economic data before it makes a decision on rates, but several policymakers have voiced support for more than one increase this year.

Investors will keep a close eye on Yellen's remarks as they look for fresh drivers that could push stocks higher. The S&P 500 is back in the red for the year after a five-week rally fizzled out.

Read also: European shares advance

US stocks ended flat on Monday on low volumes after data pointing to a sluggish economic recovery reduced concerns of rate hikes and a dip in oil prices pushed down energy stocks.

Crude oil fell about 2 percent as analysts forecast that U.S. stockpiles would touch record levels.

The Conference Board's consumer confidence index, due to be released at 10:00 a.m. ET, is expected to have risen to 94 in March from 92.2 in February.

Among other Fed officials speaking on Tuesday is New York Fed President William Dudley.

Shares of Lennar were up 2 percent at $47.68 premarket after the homebuilder reported results.