The NDDB had withdrawn Dhara mustard oil packets from the market on August 16 after several dropsy deaths were linked to large-scale argemone adulteration of mustard oil in Delhi and Dhara itself was tainted by an incident of adulteration at a dealer's godown. The Delhi government banned Dhara and many other brands, but has since lifted the ban after thorough tests.

An NDDB official said that although West Bengal and other eastern states had not banned Dhara, NDDB had decided to suspend sales till it could set up sophisticated testing facilities at all its packeting centres.

Prices of kachchi ghani mustard oil, the favourite cooking medium in the eastern states, had hit Rs 65 to Rs 68 a kg following Dhara's exit from the market.

The official said the NDDB has enough stocks(50,000 tonnes) to the entire needs of the local market for one month, apart from huge stocks at its headquarters in Gujarat.

He said Dhara is not mixed with cheaper edible oils such as rice bran and sesame oil, a practice resorted to by many manufacturers of branded mustard oils to keep their prices low.

NDDB has now installed high phase liquid chromatography machines at all its packeting centres to check contamination of edible oils.

The NDDB official said that, as long as Dhara had been in the market, the price of branded kachchi ghani mustard oil was around Rs 55 a kg. Dhara's absence sent prices soaring, with branded varieties touching Rs 66 a kg and loose oil Rs 58 a kg.