Mumbai, Aug 13 - A key index of the Indian equities markets extended its gains a little before noon Thursday to rule 336 points in the green and was backed by strong cues from the Asian markets.

At 11.58 a.m., the 30-scrip benchmark index of the Bombay Stock Exchange (BSE), the Sensex, which opened higher at 15,207.96 points, was at 15,356.96 points -- 336.8 points or 2.24 percent higher than Wednesday's close.

At around the same time, the S&P CNX Nifty of the National Stock Exchange (NSE), too, was trading in the positive terrain at 4,558.5 points, up 2.27 percent.

Broader market indices were also ruling in the green, with the BSE midcap index trading 2.73 percent higher and the BSE smallcap index moving up 3.35 percent.

All 13 sectoral indices on the BSE were gaining, with realty, metal and banking stocks leading the rally.

The market breadth was positive, with 1,908 stocks rising, compared to 420 declining on the BSE and 73 remaining unchanged.

All the 30 stocks on the Sensex were gaining at this time, prominent among them being ICICI Bank, up 4.