The Supreme Court in India has imposed an immediate ban on the discharge of untreated industrial waste into the River Yamuna in Delhi and in neighbouring Haryana state.

The order is likely to affect thousands of factories in the capital and the neighbouring area.

Judges B N Kirpal and S Rajendra Babu said river pollution had reached "alarming proportions."

"We direct every industry in Delhi not to discharge their effluent either into the river or into drains leading to the river," they said.

Most pollution

Monday's court order follows the publication of a report by the Central Pollution Control Board about the quantity of toxins released into the Yamuna every day by some 2,000 factories in Delhi.

The 20-km stretch of the Yamuna River in Delhi accounts for just two per cent of the river's total length, but accounts for some 71% of its total pollution, according to the board.

The board says the main culprits are small to medium-size detergent, textile, small engineering, and auto factories.

The head of the board, R C Trivedi, described the court ruling as "a major victory."

Enforcement

Environmentalists in India have also welcomed the move, but pointed out that enforcement could prove difficult.

Rajat Banerjee of the Centre of Science and Environment said it would not be easy to track down small-scale plants which discharged effluent on the quiet into municipal drains.

"Their whole business is covert," he said

"Most of them are not registered establishments so they can close shop for a month or so if there is a crackdown and resurface later when the heat is off."

Previous attempts to curb pollution in India have often had only limited success, leaving environmental groups fighting an uphill struggle.