Nevada environmental officials continue to say they might not allow a massive non-nuclear explosion planned for June 2 at the Nevada Test Site because the federal government has failed to provide complete information about the possible fallout.

"A number of questions have been raised regarding radiological contamination" that could be injected into the atmosphere from the test, state Air Pollution Control Bureau Chief Michael Elges wrote in a letter Friday to Kathleen Carlson, manager of the National Nuclear Security Administration's Nevada Site Office.

The NNSA is hosting the test, known as Divine Strake, for a Defense Department agency.

The letter seeks all radiological surveys of the tunnel complex area, 85 miles northwest of Las Vegas, where the Defense Threat Reduction Agency is preparing to detonate 700 tons of ammonium nitrate and fuel oil in a pit near the top of a ridge.

In addition, the state Air Pollution Control Bureau wants a detailed analysis of surface and below-ground contamination within a several mile radius of the blast site.

"As our technical evaluation process proceeds, more information may need to be provided," Elges' letter states. He noted that the bureau can't guarantee that a final decision on allowing the test to proceed will be made before June 2.

The Nevada Division of Environmental Protection, or NDEP, which includes the bureau, sent a letter dated April 7 to the NNSA stating that it "is prohibited from allowing this test to proceed until authorization from NDEP (the division) has been received."

The information had been requested a year ago, but at the time of the April 7 letter the NNSA had not responded to the request. Since then, the NNSA has submitted a 35-page document containing charts of pollutants and plume maps.

Documentation of hazardous air pollutants that could be carried in the explosion's dust-filled mushroom cloud is required under an air quality permit for operating the government's test site.

State environmental officials want to ensure that state or federal air quality regulations will not be violated, according to Dante Pistone, a division spokesman.

"We will require field monitors to ensure the accuracy of NNSA's claim that no radioactive materials will be resuspended into the atmosphere," he wrote in an e-mail. "In addition, the Desert Research Institute will be contracted to provide third-party monitoring at those locations."

In an e-mail Wednesday, NNSA spokesman Darwin Morgan said, "We have and are providing information to the state. As they have questions about the data and information we have provided them, we are responding to those queries.

"We are continuing to work cooperatively with the state on a daily basis to ensure that all available responsive information is provided and explained to them," Morgan said.

On a recent tour of the test site, NNSA officials distributed an aerial photograph of a five-mile radius from the Divine Strake pit that shows most hot spots for radioactive surface contamination are more than four miles away. There is, however, a muck pile on the surface 1.6 miles away left from six nuclear tests below ground between 1962 and 1971.

Government scientists have said the purpose of Divine Strake is to fine-tune their confidence in the ability of existing weapons to defeat deeply buried, hardened targets such as a limestone tunnel containing weapons of mass destruction.

They insisted the effort is not aimed at developing new nuclear bunker-buster bombs. Instead they intend to obtain data on how shock waves from conventional explosives travel through bedded limestone to assess the capabilities of existing weapons and for exploring more powerful conventional explosives.

Rep. Shelley Berkley, D-Nev., is not convinced of the scientists' claims about Divine Strake's purpose. On Wednesday she sought written assurance that the blast is not part of a program to develop new nuclear weapons.

In a letter to James Tegnelia, chief of the Defense Threat Reduction Agency, Berkley said she would not support the experiment until she receives a satisfactory response.

Berkley also expressed concern that the Defense Threat Reduction Agency, a branch of the Department of Defense, has not yet proved the blast will conform with the state's air quality guidelines.

"As I have stated publicly, I cannot support the Divine Strake test until federal agencies provide all information needed by the state to determine all potential environmental effects of the test," Berkley said in the letter.

An e-mail seeking comment from the Defense Threat Reduction Agency was not immediately answered.

Berkley met with Tegnelia April 6 in her office. Although she said the meeting went well, she stopped short of endorsing the experiment.

Rep. Jim Matheson, D-Utah, also has expressed reservations about the test, but other members of the Nevada congressional delegation have said they are convinced the detonation will not cause harm.

"There's nothing that's going to happen as far as dispersing anything bad in any place," Sen. Harry Reid, D-Nev., said.

Reid said he is convinced the test has nothing to do with reports that the United States might bomb Iran to stop that country's development of a nuclear weapon.

Tony Batt of the Stephens Washington Bureau contributed to this report.