NEW YORK (CNNMoney.com) -- A Senate panel grilled a key government energy expert Tuesday over why the Bush administration plans to continue adding to the nation's oil reserve as the price of crude spikes near $100 a barrel.

Lawmakers also accused the administration of turning a blind eye to the role that oil speculators are playing in driving up prices.

The Department of Energy is planning to spend nearly $1 billion in 2008 to boost the amount of oil the nation holds in its 750 million barrel Strategic Petroleum Reserve.

One industry analyst, testifying before a Senate panel made up of energy and homeland security and government affairs committee members, said the government may cause a significant increase in the price of crude over the next six months by filling the reserve with the easily refined and most valuable light, sweet crude.

"If I'm right, we could see prices go to $120 a barrel," said Philip Verleger, president of the Aspen, Colo.-based energy consulting firm PK Verleger.

The lawmakers blasted the Bush administration for undertaking such action in light of the high price and with seemly little analysis on what effect this could have on prices.

They asked Guy Caruso, the head of the Energy Information Agency, the statistical arm of the Department of Energy, if top DOE officials had consulted him on the impact of filling the strategic reserve.

Caruso, who was nominated by President George W. Bush, said he had not been contacted. The EIA was set up by Congress in the 1970s by a law that aims to protect its role as an independent service monitoring the supply and demand for oil.

"The law says filling [the reserve] must not result in excessive costs," said Sen. Susan Collins, R-Maine. "It seems evident to me the department is not complying with the law."

Collins was joined by Sen. Carl Levin, D-Mich.

"It looks to me like the DOE is ignoring the law and the pocket book of Americans - this is a reserve," Levin said.

Caruso said he did not believe that filling the reserve would have a big impact on prices, as it is only taking about 20,00 barrels a day off world markets, compared to other disruptions in places like Nigeria that have taken up to 500,000 barrels of light, sweet crude off the market without too much of an impact on price.

The senators told Caruso, whose agency does not control the reserve, to look into its potential price impact and to ask DOE why it hadn't contacted his agency.

Caruso was also taken to task for his stance on energy speculators, the effect they are having on prices and the limited information his agency could provide on the subject.

He said that speculative investment - banks, hedge funds and others buying oil - is having just a marginal effect on prices. The main reason prices are so high is tight supply and demand, he said.

Several senators and other witnesses disagreed.

"The commodities futures markets have become an orgy of speculation, a carnival of greed," said Levin. "I see no justification for oil to be at $100 a barrel."

"The current high oil prices are inflated by as much as 100 percent," said Fadel Gheit, a senior energy analyst at Oppenheimer, an investment firm. "The price surge is the result of excessive speculation."

Caruso said EIA has looked into speculation and said it is hard to say exactly how much it is contributing to high prices. He said it was the role of the Commodities Futures Trading Commission to regulate oil trading.

Sen. Ron Wyden, D-Ore., wasn't satisfied.

"You've got hundreds of people, but you can't even put a few people on this role of looking into speculation," Wyden said.

Wyden suggested that EIA disclose in its weekly inventory survey the size of individual company oil stockpiles, a suggestion that Caruso said would violate the confidential nature of the survey.

Gheit, the Oppenheimer analyst, said that lowering the amount of oil traders could buy with borrowed money, requiring investors to hold oil contracts for a certain period of time, and limiting the amount of contracts that could be bought under one name could help reduce the effect of speculative money on prices.