Mumbai, March 12 (IANS) The key Indian equity indices opened on a positive note on Friday with the BSE Sensex surging over 500 points.

Sensex rose as much as 542 points to touch an intraday high of 51,821.84 points.

Healthy buying was witnessed in metal, banking and oil and gas stocks.

Around 9.18 a.m., Sensex was trading at 51,723.51, higher by 444 points or 0.87 per cent from its previous close of 51,279.51.

It opened at the day's low of 51,660.98 points.

The Nifty50 on the National Stock Exchange was trading at 15,298.40, higher by 123.60 points or 0.81 per cent from its previous close.

The top gainers on the Sensex were Larsen & Toubro, ONGC and HDFC Bank, while the major losers were Bajaj Auto, Sun Pharmaceutical Industries and Hindustan Unilever.

--IANS rrb/sn/dpb