WASHINGTON (CNN) - U.S. Sen. Frank Lautenberg has asked the Senate Governmental Affairs Committee to formally investigate a contract awarded to Vice President Dick Cheney's former firm to rehabilitate and operate Iraq's oil industry.

Lautenberg, a New Jersey Democrat who sits on the committee, said Friday he was "concerned about the lack of transparency" in awarding the contract to a subsidiary of Halliburton Co. (HAL: up $0.19 to $23.70, Research, Estimates), where Cheney was chief executive officer before becoming President Bush's running mate in 2000.

"I believe that a thorough congressional investigation will help establish standards as we continue in the process of rebuilding an economically independent and prosperous Iraq," Lautenberg said in a letter to the committee's chairwoman, Sen. Susan Collins, R-Maine.

Cheney's office and the White House have repeatedly denied that they had any involvement in the U.S. Army Corps of Engineers' decision to award the contract to Kellogg, Brown & Root in March, without competitive bidding.

Corps officials have said they gave the contract, worth up to $7 billion, to the Halliburton subsidiary because it already had assets in the region and had the expertise to put out oil well fires and repair Iraqi oil facilities.

However, earlier this week, Corps officials acknowledged that the contract, which has no set time limit or dollar amount, allows KBR to actually operate Iraq's oil fields and distribute its oil, rather than just putting out fires and making repairs.

Responding to questions from Rep. Henry Waxman, D-Calif., Corps of Engineers Lt. Gen. Robert Flowers said the $7 billion value of the contract was based on a worst-case scenario that Iraqi oil facilities would be heavily damaged in the war, which did not happen.

Flowers also said the scope of the work performed under the contract would be set by the government, not KBR.

Lautenberg wants the Senate committee to hold hearings to probe why the contract was awarded without bidding, why information about the scope of the contract was initially withheld and whether there is any more information that has not been disclosed.