The demolitions in Delhi follow a High Court order

One policeman was killed and 15 hurt when residents of a slum in Calcutta reacted angrily to eviction notices.

In Delhi, thousands of traders observed a one-day strike in opposition to the demolition of illegal structures by municipal authorities.

Sporadic clashes also took place in some areas where residents were being evicted from homes in the capital.

Suspended

Police in Calcutta say residents started throwing stones at officers who had arrived to help authorities remove people from slums near the Dhakuria and Tollygunge railway stations, land that belongs to Indian Railways.

Officials say they detained 20 people.

The eviction drive followed a High Court order to clear illegal occupants by the end of the year.

The slum dwellers said they were not informed about the eviction drive. They also claimed police beat them and injured several residents.

The eviction drive has been suspended until Wednesday morning.

In Delhi, traders said there was a total shutdown in 480 of the 500 markets in response to a High Court order to demolish 18,000 illegal buildings within four weeks.

Residents and traders say city officials did not raise objections when the structures were built. Some threw stones at state buses.

Secretary General of the Confederation of All India Traders Praveen Khandelwal said he did not consider the structures "illegal" but said they had been constructed because of the "poor planning" policies of the Delhi government.

He said the government did not have a proper development policy and had not upgraded its infrastructure to meet the increase in Delhi's population.

He said Tuesday's strike would cost businesses two billion rupees ($44m).