The benchmark BSE S&P Sensex index has declined by nearly 600 points amid doubts over Parliament's approval for key tax reform Goods and Services Tax (GST) bill and fears over interest rate hike in the US as early as next week.

For the week ended 11 December, the Sensex closed at 25,044.43, down 593.68 points, while the 50-share Nifty declined by 171.45 points to end 7,610.45.

The sell-off was also partly driven by falling commodity prices, with crude oil prices declining to seven-year lows. Weak commodity prices have weighed heavily on the share prices of mining companies.

"Sharp selling pressure across the world markets ahead of US Fed policy, continued fall in commodity prices worldwide raising concerns over global slowdown, continued selling pressure by foreign portfolio investors, logjam of winter session of Parliament, losing hopes of passage of GST Bill and weakening of rupee against dollar has butchered the indices during the week," The Finance Express quoted Gaurav Jain, director, Hem Securities, as saying.

Investors who remained optimistic over the passage of GST bill in Rajya Sabha before the start of winter session of Parliament are now skeptical following the controversy over the National Herald case. Congress accused the Modi government of following a 'political vendetta' against the Gandhi family.

The Delhi High Court has summoned Congress president Sonia Gandhi and her son Rahul Gandhi to appear before the court on 19 December on allegations of illegal acquisition of property worth Rs. 5,000 crore of the National Herald newspaper.

Markets also remained under pressure ahead of the US Federal Reserve meeting next week. The US central bank, which meets on 15-16 December, is widely expected to raise interest rates for the first time in more than seven years. It is well known that such a move could lead heavy outflows from emerging markets including India.

"The Federal Reserve will meet next week. The broad consensus is they will raise their policy rate for the first time since 2006. The pace of rate hikes is likely to be gradual. We expect the top-band for the federal funds rate to rise to 1.25% by the end of 2016," said TD Economics in a note.

Meanwhile, markets will also closely monitor the domestic data releases after the industrial activity showed a sharp improvement in October. The Index of Industrial Production (IIP) for October released on Friday showed that the industrial output surged 9.8% in the month, reaching its highest level since October 2010.

Data for retail and wholesale price inflation for November will be released next week and analysts expect the retail inflation to come at over 5% due to increase in food prices.