The Rs 1,000 crore difference is due to the $30 per barrel price taken for the purpose of calculating the oil pool deficit when the actual average crude import price in the first half was at $28.5 per barrel.

The overall deficit for the full fiscal 1999-2000 projected at Rs 23,600 crore has also been calculated at a price of $30 per barrel. With the OPEC countries promising to bring down crude oil prices further from the current level of around $30 per barrel, the oil pool deficit for the second half of the financial year is also likely to be lower than the projections.

Government sources said the difference of Rs 1,000 crore in oil pool deficit in the first six months and the expected fall in crude oil price in the second half of the year would come handy in cushioning the impact of a partial rollback in petro product prices and containing the overall deficit below Rs 6,000 crore.

As per official sources, a $1 per barrel reduction in global crude oil prices would bring down the oil pool deficit roughly by Rs 1,200 crore annually.

If by the year end, the average of crude oil prices stand at an average at $28 a barrel, then the petroleum ministry's estimated oil pool deficit of Rs 23,600 crore (at $30 barrel) will come down by Rs 2,400 crore.

It may be noted here that there is usually a difference of $2 per barrel on the rate of crude of London Brent and Dubai crude. Oil imports are carried out as a mix of Dubai and Brent crude in the ratio of 54:46. Therefore, while calculating the oil pool deficit, average of Dubai and Brent crude prices is taken at the given ratio. As for instance, two days back, the price of Brent crude was $31.13 a barrel and that of Dubai crude was $27.35. The actual imports were, therefore, carried out at an average of $29.09 a barrel.

The Prime Minister may have succeeded in postponing the rollback issue. However, owing to demands from Trinamool Congress, he may have to make some corrections in the recent increase announced by the union petroleum minister Ram Naik.

Meanwhile, union petroleum ministry sources have hinted at the possibility of a reduction of 50 paise per litre in kerosene prices and Rs 5 per cylinder in LPG prices after the Cabinet meeting scheduled for today.

A 50 paise reduction in kerosene prices would translate to Rs 300 crore burden on oil pool deficit in the next six months.

On the other hand, a Rs 5 per cylinder reduction would mean a Rs 150 crore additional burden over six months. So, a total of Rs 450 crore burden is what the petroleum ministry will have to bear on acount of this roll-back in kerosene and LPG prices.

However, tinkering with diesel pries at this stage is what is worrying the petroleum ministry the most. A Rs 1 per litre reduction in diesel prices alone would have a impact of Rs 2500 crore in the next six months.

Even if diesel prices are brought down by Rs 0.50, it will have an impact of Rs 1,250 crores.