Operations at India's public-sector banks and many factories were hit for a second straight day by a general strike called to protest against the government's pro-market reforms.
The Associated Chambers of Commerce and Industry (ASSOCHAM), a prominent business group, estimated losses from the two-day stoppage at 260 billion rupees ($4.8 billion).
Eleven unions called the walkout in protest against the measures which they condemned as "anti-poor" and said were likely to cost jobs and raise prices.
While the impact of the stoppage was felt mainly in heavily unionised state-run institutions, analysts said it underscored discontent among workers.
"The government must sit down with the workers and hear them out because it cannot afford to ignore this class any more with general elections due in 2014," Shubha Singh, a New Delhi-based political analyst and writer, told AFP.
Leaders of two main leftist parties said they were boycotting the opening session of parliament on Thursday in solidarity with the strikers.
The government's reforms include opening the retail, insurance and aviation sectors to wider foreign investment in a bid to spur a sharply slowing economy.
They also involve raising prices of subsidised diesel and reducing the number of discounted cooking gas cylinders to trim a ballooning fiscal deficit.
The government is already under pressure over an economy growing at its weakest pace in a decade and widespread allegations of corruption.
Attendance at some government offices was thin and many education institutes were closed as teachers' unions joined the strike. Universities cancelled exams set for Thursday.
Operations at India's state-run banks were also halted.
Top carmaker Maruti, which has a history of labour unrest, declared a holiday to avert trouble while two-wheeler manufacturer Hero MotorCorp gave workers a day off.
The All India Trade Union Congress said millions of workers were taking part in the strike and called on them to keep up pressure on the government, already facing a hostile opposition in parliament.
In an industrial area of New Delhi, protesters shouted slogans against the government and pelted stones at factory buildings to force their shutdown.
Police arrested nearly 100 people in Noida, a sprawling suburb of Delhi where vehicles were torched and factories vandalised on Wednesday.
ASSOCHAM slammed protesters for the violence.
"Pictures showing burning of cars and other industrial property spread all over the print, electronic and social media really scares investors," it said in a statement.