Calling the Goods and Services Tax (GST) bill a 'brahmastra' for the Indian economy, industry body Assocham has appealed to the Opposition parties to give support to the passage of the tax reform bill in the winter session of Parliament that started on Thursday.

"Goods and Services Tax is a key 'brahmastra' for our GDP. Lawmakers across parties should pass the Constitutional Amendment Bill on GST without further delay," the new Assocham President Sunil Kanoria said.

In the monsoon session of Parliament, the Modi government was forced to delay the landmark GST Bil, after facing strong opposition in the Rajya Sabha, where it does not have a majority.

Some analysts warn that further delay in the passage of key bills could lead to fund outflows from the country.

Kanoria said the domestic economic growth was hampered by a slowdown in demand, impact from Paris terror attacks and a crash in commodity markets.

"Timely implementation of GST" would increase the gross domestic product (GDP) growth by 1.5 to 2% and it would help in making the country as "one India rather than divide India", Kanoria said.

"GST will harmonise indirect taxes by doing away with multiplicity of taxes. It will also reduce cost of production, which will be then passed on consumers, thus lowering inflation. More striking would be the display of a political unity and the will to rise up to national cause," he said.

Saying that the Opposition should stick to earlier stance on the bill, he urged the Congress party to "rise up to the national call" and help the passage of GST bill in Rajya Sabha.

"If the Congress party or any other national or regional party has some specific concerns, the government should look into the same and address it as far as possible. There can always be a middle ground," PTI quoted Kanoria, as saying.

He expected the India's GDP growth to come at  7.2 % to 7.3% in the current fiscal year.