The Indian rupee tumbled by another 12 paise to nearly five-week low of 40.17/18 against the American currency on Thursday as oil companies stepped up dollar purchases after oil prices hit a new record high yesterday.

Forex dealers said the local currency buckled under pressure after a promising start at 40.00/01 a dollar as oil refiners frantically covered dollars to meet their month-end import bills amid inadequate supplies.

At the Interbank Foreign Exchange (forex) market, the rupee moved in a wide range of 40.00 and 40.1850 during the day as all factors worked against the Indian unit.

Foreign banks too bought dollars heavily during the day, said dealers from private banks.

Asian equity markets also came under pressure after a buoyant start and ended mixed. Indian benchmark Sensex was almost flat today.

The sky-high global oil prices was the prime cause for the rupee's sharp fall today, traders said.

Oil companies were forced to make dollar purchases for their import payments at the month-end, they added.

World oil prices paused within sight of USD 120 a barrel level in Asian trade after a mixed report on US energy stockpiles.

Earlier in the month, the central bank preferred to hold rupee to around 39.90 level against dollar before raising the Cash Reserve Ratio by 50 basis points to 8.0 per cent in a bid to contain rising inflation rate.