India's petroleum ministry has rejected a report by authorities in Karnataka that some petrol pumps in the state sold fuel blended with more ethanol than the permitted 20 per cent limit, saying its own tests show supplies meet national standards.

Karnataka's food and civil supplies minister, Rizwan Arshad, said on Friday that four in five pumps surveyed in the state were selling petrol with ethanol above the 20 per cent limit, with samples reaching 31.2 per cent. The findings raised fresh concerns about fuel quality as India expands E20, a petrol blend containing 20 per cent ethanol, as part of Prime Minister Narendra Modi's drive to cut crude imports, lower emissions and support domestic ethanol producers.

The ministry said on Saturday that 893 E20 samples collected from 27 states and union territories had all tested within the prescribed 19 to 21 per cent range. All 56 samples tested in Karnataka, covering different locations and all three state-run fuel retailers, recorded ethanol between 19 and 20 per cent, with an average of 19.30 per cent.

Retailers question the state's testing

State-run retailers Indian Oil, Bharat Petroleum and Hindustan Petroleum disputed the findings and asked for independent testing of Karnataka's samples. They said the reported results were not supported by tests carried out under the prescribed statutory and technical procedures, and questioned the sampling and testing methods used in the state's October exercise, which they said took place without their representatives present.

Opposition leader Rahul Gandhi called the matter "petrol theft" and urged Modi to disclose actual ethanol levels and act against companies that over-blend.

The ministry also questioned claims of an annual consumer loss of about 62,000 crore rupees from lower mileage and 39,000 crore rupees in vehicle repairs, saying the estimates were not scientifically established.