NEW DELHI (Reuters) - India's communist parties, which keep the federal government afloat, said on Wednesday they will oppose any move to raise the regulated price of petroleum products despite soaring crude oil prices.

"The government should reduce taxes instead of raising prices," Sitaram Yechury, a senior communist leader told reporters after a meeting with oil minister Murli Deora and top petroleum ministry officials.

He said the government should protect the common man by slashing taxes, which account for 55 percent of the petrol price and 34 percent of the diesel price.

Deora said he had not formally discussed a price increase with the finance ministry, but officials said the meeting with communist leaders was held to build a political consensus for a moderate increase in retail prices.

Oil ministry officials said refiners were reporting losses, losing their credit ratings and would require heavy subsidies from state exploration firm Oil and Natural Gas Corp..

State refiners -- Indian Oil Corp., Hindustan Petroleum Corp Ltd. and Bharat Petroleum Corp. Ltd. would suffer a revenue loss of nearly 750 billion rupees ($16.7 billion), officials said.

The state-administered price of petrol and diesel, frozen since September, was adequate to compensate refiners if crude oil prices fall by $20 a barrel, officials said.

U.S. crude held above $70 a barrel on Wednesday, almost $5 below a record high touched last month but still up more than 15 percent since the start of the year.

The government, headed by the Congress party, has promised a decision on raising fuel prices, frozen since September, by the end of May.

India's communists, with 61 of 545 seats in the lower house of parliament, are expected to have performed well in elections in five states for which results will be declared on Thursday.

If so, their influence over the government -- which they support from outside the ruling coalition -- may increase.