The Oil and Natural Gas Corporation's oil reserves trebled in the past two years to 307 million tonnes, which is equivalent to over four years of oil imports and almost three years of domestic oil consumption.

This was mainly on account of the stakes purchased by the state-owned firm in overseas oilfields.

Of the 307 million tonnes of oil reserves, 117 million tonnes accrued in 2002-03, while 191 million tonnes were amassed in the previous year.

In 2002-03, about 76 million tonnes of the company's oil reserves were in the overseas oilfields, while 40 million tonnes were in domestic fields.

"The accretion in reserves during the past two years, against a cumulative production of 100 million tonnes, is highly encouraging from the point of sustained growth of the company as well as national oil security," said Subir Raha, chairman and managing director of ONGC.

The government has been making elaborate plans for oil security since September 2002, when war clouds began gathering in the Persian Gulf, fearing disruption in the supply of crude.

India imports about 70 per cent of its crude requirements, and a major portion of it comes from the Gulf countries. In 2001-02, crude imports stood at 78.71 million tonnes, against a consumption of 107.27 million tonnes.

ONGC's oil equity abroad is in the Sakhalin-I project (Khazaskhstan) and the Greater Nile Oil project in Sudan.