Mumbai, Dec 15 (IANS): Key Indian equity indices opened on a cautious note on Tuesday, reflecting the mood ahead of the crucial US Federal Reserve meeting over the next two days that is expected to raise interest rates, potentially making it attractive to invest money in the American economy.

Against the previous close at 25,150.35 points, the sensitive index (Sensex) of the Bombay Sock Exchange (BSE) opened slightly higher at 25,186.68 points.

Immediately thereafter, the index was ruling at 25,183.93 points, with a small gain of 33.58 points, or 0.13 percent.

At the National Stock Exchange, the broader 50-share Nifty opened slightly higher and was ruling at 7,651.55 points against the previous close at 7,650.05 points.

Minutes after the opening bell, the index was ruling at 7,651.55 points, with a negligible gain of 1.50 points, or 0.02 percent.

On Tuesday, the Sensex had 105.92 points or 0.42 percent, while the Nifty gained 39.60 points or 0.52 percent.

In other Asian markets, too, the mood was cautious, and the key indices were ruling sans any major movements.

"US markets closed in the green helped by a rebound in the crude oil prices. Crude oil prices fell below $35 a barrel but settled higher for the first time in seven sessions. European shares slid sharply led by a renewed dip in energy stocks as oil prices gyrated," Angel Broking said.

"Indian shares closed in the green as the sharp surge in industrial production in October 2015 lended support to indices amid weak global sentiments," the brokerage said in an analysis ahead of the opening bell in Indian stock markets.

The Federal Open Market Committee of the US Fed is set to hold its eighth and final meeting for this calendar year on Tuesday-Wednesday, and there are some wide expectations that, Janet Yellen, the chair of its board of governors, will raise interest rates this time around after months of "will she, will she not".