By Habib Beary BBC correspondent in Bangalore

Thousands of Dalits are employed in the filthy work

Civic authorities have introduced a machine to help perform the task in the poorer neighbourhoods of the city.

The appliance is the first of many such pieces of equipment which the city will use to remove human excrement - a task performed until now by poor workers.

There has been a long tradition of misusing groups of jobless, low-caste Hindus (or Dalits) for the filthy work.

'Trial basis'

Mayor CM Nagaraj said many more machines will be bought to cover areas in the city which lack an underground sewage system.

"This has been bought on a trial basis. If it works well, we will have more such machines," Mr Nagaraj said.

Workers clear sewage at night

The mayor told the BBC it was regrettable that humans were continuing to be used for cleaning toilet pits.

"This practice has to end," he said.

Although the practice of using Dalits to clean out sewage pits is common in many parts of India, it had attracted much criticism in India's Silicon Valley which is home to many global and national software companies.

Human rights activists see the work as an extension of the "night soil system", banned by the state government in 1973.

Stench

Corporation authorities plan to undertake a survey to find out how many people are employed in pit cleaning and take steps towards their rehabilitation.

Ashok Salappa, a member of the government-run Safai Karmachari (sweepers) Monitoring Committee, estimates the number of Dalits employed in cleaning toilet pits in Bangalore to be between 10,000 and 15,000.

The high-tech image of Bangalore

They are called in when the pits become blocked, and work in the dead of night.

After swilling strong alcohol to ward off the stench, one member of the group gets into the pit and empties it with buckets or cans and the refuse is taken away by other people working alongside.

Watched by civic officials and groups of residents, the machine was put to use at Venkateshwarapura in the eastern part of the city.

Costing 450,000 rupees ($9,500), it has been developed by Cam Avida, a city-based company.