Indians may think twice before gulping down a glass of milk after the country's food safety regulator found most samples collected in a survey were either diluted or adulterated with products including fertilizer, bleach and detergent.

The study, conducted this month by the food safety and standards authority of India, found milk was adulterated with skimmed milk powder and glucose, or more shockingly hydrogen peroxide, urea and detergent.

Hydrogen peroxide is used in bleach, while urea is commonly used in fertilizer.

"Consumption of milk with detergent may cause health hazards and indicates lack of hygiene and sanitation in the milk handling," the regulator said in a report.

"Addition of water not only reduces the nutritional value of milk but contaminated water may also pose health risks."

A health ministry official declined to comment on the report.

India has long struggled with adulteration of food and milk by unscrupulous traders. Almost 70 percent of the 1,791 samples taken nationwide were contaminated or watered down, according to the report.

Out of 33 Indian states, non-fat adulterants were found in all the milk samples from West Bengal, Orissa and Jharkhand. This adds to concern about West Bengal's faltering health and safety standards. In December, an adulterated batch of bootleg liquor killed at least 125 drinkers in the eastern state.

The deaths came a few days after a hospital fire killed 93 people in the state's capital Kolkata.

New Delhi fared worse than most states, with as many as 70 per cent of the samples tainted. The western state of Goa and eastern state of Puducherry conformed to the standards, with no indication of adulteration in their milk.