WASHINGTON — The controversial, government-sponsored weapons test known as Divine Strake has been put off at least until next year, the Defense Threat Reduction Agency announced Tuesday.

The National Nuclear Security Administration is still working on its environmental studies regarding radiation exposure related to the blast, but the Defense Threat Reduction Agency has stopped preparing the Nevada Test Site for the experiment, designed to produce ground motion and shock wave data on penetrating hardened and deeply buried targets.

"The earliest point at which the Divine Strake experiment can be conducted would be at least several months into calendar year 2007," according to the agency announcement sent to congressional offices.

The test was supposed to take place June 2, but a lawsuit filed by opponents pushed it off until June 23. Then the National Nuclear Security Administration, which oversees the Nevada Test Site that is home to the experiment, withdrew an environmental assessment of the program, pushing it off to an undetermined date.

The detonation of 700 tons of explosive ammonium nitrate and fuel oil slurry would have created a huge mushroom cloud and critics feared it would kick up radioactive fallout left from atmospheric and below-ground nuclear weapons tests and lead to the development of low-yield nuclear "bunker-buster" bombs.

The proposed blast raised concerns by Utah and Nevada congressional delegations and prompted protest petitions by hundreds of people.

Tuesday's announcement, which generated a cautious response by opponents who also felt validated by the delay, said the government would conduct the experiment only if it can be "conducted safely," according to environmental laws and if there is "a favorable court ruling." The agency said plans on public hearings, the exact schedule of the experiment and other actions will be determined.

"This delay is reflective of a cancellation of the planned explosion," said Robert Hager, the plaintiffs' attorney in the case against the Defense Department on the test. "The agencies' pursuit of data regarding background radiation and global fallout is a dead-end path that will not put to bed public health concerns about re-suspension of radioactivity. People do not die from inhaling background radiation.

"Until the agencies analyze what is in the soil, and disclose that data, this blast will never be allowed by the court."

The agency may also opt to move the experiment somewhere else. On Tuesday, Sen. Orrin Hatch, R-Utah, met with the agency's director, James Tegnelia, who told the senator that he would assess other locations for the blast.