NEW DELHI (Reuters) – India is committed to developing its nuclear energy capability and other sources of power as its oil bill will impose an “unbearable burden” as growth continues, the prime minister said on Monday.

Manmohan Singh’s comments came as his government faces its worst crisis since coming to power in 2004, with communist allies angered over a nuclear energy deal with the United States and threatening to withdraw their support.

“As we grow, our growing … bill for imported crude oil will put unbearable burden on our economy,” Singh said at an inauguration ceremony for an energy research institute.

“We need to develop all energy resources mainly coal, gas, oil, hydro and nuclear along with renewable, such as wind and solar,” he said.

“From a long-term perspective, nuclear energy and solar energy can play an important role in addressing our energy security needs. Our government is committed to the development of nuclear energy.”

India imports 70 percent of its oil needs and rising global crude prices pose policy challenges for Asia’s third-largest economy, which has grown at an average 8.6 percent in the past four years.

That expansion has been accompanied by a rapid rise in demand for energy.

Singh said it was important to create awareness about the economics of energy. “Each time our utilities have to raise rates and our oil companies have to raise prices, extraneous considerations come in,” he said.

“I urge all political parties to appreciate the vital interest of pursuing a sound energy security strategy. India is on the move and we must be able to address its growing energy demand.”

A bloc of four communist parties has 60 lawmakers in India’s lower house of parliament, and while not a part of the ruling coalition, they shore it up from outside.

They have warned of “serious consequences” for the government if it presses ahead with the nuclear deal, which still needs to be approved by the U.S. Congress and international bodies.

The pact with Washington aims to end three decades of American sanctions on nuclear trade with India but the communists say it would undermine India’s nuclear security and sovereignty.

India may review retail fuel prices after the monsoon session of parliament ends in mid-September if global prices remain high, oil ministry officials say.