Protests crippled the financial world
Wednesday's general strike in India cost the country's economy 15bn rupees ($320m; £196m) in terms of lost production, the Press Trust of India has reported trade unions as saying.
"We might go for longer strikes if our demands are not met," PTI quoted Centre for Indian Trade Unions general secretary MK Pandhe as saying.
"But for that we [the trade unions] will have to sit together to make enough preparations since any hasty decision could derail the country's economy."
Up to 50 million workers in India went on strike for one day in protest at government plans to privatise state-owned businesses.
The one-day stoppage severely affected the banking, transport, insurance and mining sectors, and brought Calcutta to a virtual standstill as protesters marched through the streets.
The strike was called by trade unions including the All India Trade Union Congress (AITUC), Centre for Indian Trade Unions and the Hind Mazdoor Sabha.
They are calling for a halt to the government's ongoing privatisation and plans to change labour laws.
The strike was described as the biggest show of discontent in recent times against the central government's economic policies.
The government's privatisation plans aim to raise 132 billion rupees ($2.75bn) by selling off state-run companies in the year ending March 2004.
But protesters claim this is leading to huge job losses. They are also angry at plans to allow state-run companies to fire workers and reduce deposit rates for pension funds.
BBC correspondent Sanjeev Srivastava said the government was unlikely to give in to union demands immediately but that the strike could slow down reforms.
But he said the government may not want to annoy the trade unions in the run up to national elections next year.
The government has said labour reforms are needed to allow Indian industry to compete with countries such as China.
And it says privatisation is needed to bridge the government's increasing fiscal deficit.
But plans to sell national oil firms have been strongly rejected by key ministers including defence minister George Fernandes and petroleum minister Ram Naik.