Mumbai, Sep 26 (IANS): A key Indian equities index Monday slipped below the 16,000-point mark amid weak global cues, a continuing slide in the value of the rupee and pressure on the United Progressive Alliance ((UPA) government over the telecom airwaves case.

The 30-scrip sensitive index (Sensex) of the Bombay Stock Exchange (BSE) opened at 16,209.19 points against its previous close at 16,162.06 points, but slipped into the red soon after.

About an hour-and-half into trading, the benchmark index was ruling at 15898.45 points, with a loss of 263.61 points, or 1.69 percent. As many as 28 out of the 30 shares that constitute the Sensex basket were in the red.

Over the past year, the index is down nearly 1,500 points, or a little over 20 percent.

At the National Stock Exchange, the situation was no better with the broader 50-share S&P CNX Nifty ruling at 4,784.65 points, down 83.10 points, or 1.71 percent over the previous close.

While rupee was at ruling at 49.57 per dollar, against its close at 49.42 Friday, the bullion market was also weak, with gold and silver down.

Apart from the trouble in the Eurozone, Greece and the US, sentiments were also affected by the political rift caused by a letter from the finance ministry to the Prime Minister's Office, that is seen just short of indicting Home Minister P. Chidambaram in the second generation (2G) spectrum case.

In the note, the finance ministry says Chidambaram, as finance minister in 2007, could have prevented spectrum from being given away at throwaway prices by insisting on its auction, implying that presumptive losses could have been avoided.