Two months ago Singh said there had been complaints of large-scale genetically modified (GM) soyoil imports and the government intended to curb the inflow.

Some traders said at the time that any curbs on soyoil imports could increase domestic edible oil prices and boost local oilseeds output but could also raise palm oil imports.

India, the world's largest edible oil buyer, imports soyoil from South America and palm oil from Malaysia and Indonesia.

It imported a record 4.83 million tonnes of edible oil in 2000/01 (November-October), up from 4.49 million a year earlier. Of this, it bought 1.4 million tonnes of soyoil and 2.95 million tonnes of palm oil in 2000/01.

Singh said the environment ministry should take steps to oblige importers to declare whether the commodity being imported was of GM origin. Traders would also need to get a permit from the ministry for GM food imports.

Singh, in a letter to Prime Minister Atal Behari Vajpayee in March, had said India was importing large quantities of soyoil from Argentina, Brazil and the United States, where use of transgenic soybean varieties was widespread.

"There is, therefore, a strong likelihood that the soyoil being imported by us from these sources has been extracted from transgenic soybean," he said in his letter, a copy of which was obtained by Reuters.

Singh said yesterday there should be some system in place at customs to check whether importers were bringing GM foods.

"If they are, then we should test and decide as it can have far-reaching effects on health and biodiversity," Singh said.

Singh said it was up to the environment ministry to establish laboratories to ascertain if GM material was present in imported oil.

In April, Food Minister Shanta Kumar described the testing of soy oil for GM sources as impractical and said any curbs on GM soyoil were likely to result in a palm oil monopoly.