New Delhi - India's eastern metropolis of Kolkata Saturday imposed a ban on commercial vehicles more than 15 years old, triggering protests by transport operators who damaged buses and put up road blocks in the city, news reports said.

The ban, aimed at reducing pollution levels, affects thousands of buses, taxis and rickshaws.

As authorities started seizing 15-year-old commercial vehicles in accordance with a court order, transport operators damaged six government buses in different parts of the city, the IANS news agency reported.

Senior police official Javed Shamim told the IANS that adequate police arrangements across the city ensured that the situation was 'generally peaceful'.

Although many Kolkata residents supported the move, they were worried about how they will get to work.

Nearly 4,000 private buses, 6,800 taxis and more than 95 per cent of total 65,000 auto-rickshaws were barred from Kolkata under an order by India's Supreme Court.

According to a recent study, 70 per cent of the city's residents suffered from respiratory problems, including lung cancer and asthma.

Commuters in the city had a harrowing time as practically no auto- rickshaws plied in Kolkata. An estimated 1,000 taxis were also off the roads.

"Saturday and Sunday are government holidays. So fewer people are out on roads," college student Jyotiraditya Guha said adding, "the situation will be really bad from Monday, I do not know how I will travel".

Mamata Banerjee, leader of the state opposition Trinamool Congress party said that the withdrawal of the old vehicles should be done in phases, considering a million people comprising the transport operators, workers and their families will be affected by the ban.

"I support the environmental concerns. But the economic condition of these people will also have to be considered," she said. (dpa)