The BSE Oil & Gas index was trading 1.07 per cent down at 14,232 around 12:15 pm.
However, GAILNSE 0.35 % (India) (up 0.96 per cent), Indraprastha Gas (up 0.69 per cent) and Reliance IndustriesNSE -0.80 % (up 0.11 per cent) were in the green in the index around that time.
As per Bloomberg, Saudi Arabia promised to keep oil prices under control, signaling a supply boost approaching 1 million barrels a day is on the way to global markets.
Equity benchmarks were lacklustre owing to profit-booking amid mixed Asian cues on worries over a US-China trade war.
Benchmark BSE Sensex was 60 points down at 35,629, while the NSE Nifty50 index was down 15 points at 10,807.
Among the 50 stocks in the Nifty index, 22 were trading in the green, while 28 were in the red.
In the Sensex kitty, 13 stocks were advancing, while 18 were declining in trade.
Tata Motors, ICICI Bank and Coal India were leading among the Sensex index.