LAS VEGAS — A nuclear weapons explosion, scheduled by the government despite congressional protest and the presence of hundreds of demonstrators at the test site, was postponed today. Peace groups claimed a major victory, but official sources said the delay was due to the weather.
However, another Reagan Administration official in Washington, speaking on condition of anonymity, said that there were no weather problems and that the test had been postponed for "technical reasons."
That official refused to characterize the nature of the problem or to say whether a new date has been selected for the test.
At least 87 anti-nuclear activists, including Daniel Ellsberg, were arrested on or near the test site before the decision to postpone was disclosed.
A spokesman for the Southern California Freeze Campaign claimed that the test was called off because of their demonstration.
"This means we have won a significant victory," said John Murphy of the Freeze organization. "Even if it is postponed only a few days, it gives a chance for the moratorium."
White House spokesman Larry Speakes refused to discuss reasons for the test postponement except to say it was unrelated to U.S.-Soviet relations or planning for a summit. The test had been scheduled the same day President Reagan met with departing Soviet Ambassador Anatoly F. Dobrynin.
In Washington, congressional opponents urged the Reagan Administration to go along with a current Soviet moratorium on testing and an offer by Soviet leader Mikhail S. Gorbachev to halt all testing if the United States does.
Gorbachev declared a six-month unilateral test moratorium last July and extended it until March 31. The Reagan Administration rejected the offer of an indefinite moratorium, saying it would not work. The last U.S. underground test was conducted March 22.
'Why Not Call Bluff?'
"The Soviets have said they want to stop testing and are willing to accept on-site inspection to verify a test ban treaty," Rep. Edward J. Markey (D-Mass.) said. "Why don't we call their bluff? If we don't, history will record that it was a Soviet leader who went the extra mile toward ending the nuclear arms race and an American President who turned him down."
Rep. Thomas J. Downey (D-N.Y.) said that by conducting the test, the Administration "will take a perilous step backward in their nuclear weapons policy, placing ideology firmly ahead of national security."
The test blast, code-named "Mighty Oak," had been scheduled to be touched off at 8 a.m. on the sprawling Nevada site. No official announcement was made, but Department of Energy sources in Washington said it was delayed because of high winds and will be conducted when weather permits.
An estimated 200 anti-nuclear protesters turned out at the gates to the testing range, and 75 were arrested for crossing a white line near the site entrance. The turnout was one of the largest in recent years.