Mumbai, Mar 22 (IANS): Indian equities markets' key indices closed in the red for the sixth straight session Friday due to lingering political worries after a key ally quit the Prime Minister Manmohan Singh-led coalition government.

The 30-scrip sensitive index (Sensex) of the Bombay Stock Exchange (BSE), which opened in the red at 18,784.93 points, ended the day at 18,735.60 points, down 0.30 percent or 57.27 points from its previous day's close at 18,792.87 points.

This is the lowest closing level of the benchmark Sensex since November last year.

The Sensex witnessed a volatile session and touched a high 18,859.82 points and low of 18,669.20 points in the intra-day.

The wider 50-scrip S&P CNX Nifty of the National Stock Exchange (NSE) also closed in the red for the sixth trading sessions in a row. The Nifty closed 0.13 percent or 7.40 points down at 5,651.35 points.

The Indian stock markets were under pressure this on political uncertainties after the DMK, a key ally of the ruling United Progressive Alliance (UPA) coalition, pulled out from the government.

Both Sensex and Nifty lost almost four percent in this week's trading.

There was heavy selling pressure in realty, consumer durables and IT stocks. The BSE consumer durables index fell 2.06 percent. Realty index declined 1.31 percent and IT index closed 0.82 percent down.

The country's largest lender State Bank of India slumped 1.71 percent at Rs.2083.90. Tata Steel, down 1.68 percent at Rs.322.10; Sun Pharma, down 1.42 percent at Rs.820.30; Bharti Airtel, down 1.28 percent at Rs.294.20; and ITC, down 1.27 percent at Rs.1540.95 were among the major Sensex losers.

Prominent Sensex gainers were: Bajaj Auto, up 3.85 percent at Rs.1822.85; Jindal Steel, up 3.11 percent at Rs.351.90; Hindalco Inds, up 1.64 percent at Rs.89.65; Hero MotoCorp, up 1.52 percent at Rs.1647.95; and Tata Power, up 1.43 percent at Rs.95.85.