ASHINGTON, April 22 The White House cut 93 percent of a recent request by the secretary of energy for money to improve the security of nuclear weapons and waste, according to a letter from the secretary.

The secretary, Spencer Abraham, said in the March 14 letter to Mitchell E. Daniels Jr., the director of the Office of Management and Budget, that the request, for $379.7 million, was "a critical down payment to the safety and security of our nation and its people."

The money, for guarding nuclear weapons, weapons materials and radioactive waste under the Energy Department's supervision, was part of a $27.1 billion emergency spending bill before Congress, the second such measure to be considered since the Sept. 11 attacks.

"Failure to support these urgent security requirements is a risk that would be unwise," the letter said. The New York Times obtained a copy from someone who favors more spending on nuclear security.

But Mr. Daniel passed on to Congress only $26.4 million of the request. Congress has not acted on it.

To improve the security of weapons and weapon material in storage, the letter listed areas for which the department wanted $138.3 million. They included equipment to detect explosives in packages and vehicles entering Energy Department sites ($12 million); better perimeter barriers and fences ($13 million); and improvements in Energy Department computers, including "firewalls" and intrusion detection equipment and increasing the ability to communicate "critical cyber threat and incident information" ($30 million). The request also asked for $41 million to reduce the number of places where bomb-grade plutonium and uranium was stored. All were turned down.

Also turned down was $34.1 million for increasing security at Energy Department laboratories.

The Energy Department did get $368.7 million in the first emergency spending measure of $40 billion, which Congress approved soon after the Sept. 11 attacks. It could get more money for the items that the White House rejected, because Congress has historically been willing to spend more than the administration on nuclear security.

"If they say we need money to secure nuclear warheads, apolitically, you think we'd agree to do that," said a Congressional aide familiar with the letter.

In his letter, Mr. Abraham noted that the department designed, manufactured, assembled, stockpiled and refurbished weapons and took them apart when they were retired. (The Defense Department controls deployed weapons.)

"We are storing vast amounts of materials that remain highly volatile and subject to unthinkable consequences if placed in the wrong hands," he wrote. "These materials permeate the departmental complex."

The first emergency spending bill "helped respond to the most urgent near-term security needs," Mr. Abraham wrote. But, he added, "the department now is unable to meet the next round of critical security mission requirements."

Asked to comment on the letter, Jeanne Lopatto, a department spokeswoman, said, "We're not going to get into details of discussions we have with the administration."

She added that "our nuclear weapons complex is among the most secure facilities in the world, and we are constantly assessing and evaluating security at the weapons complex."

She said that the department might shift funds from other programs into security and that the administration could possibly request more money from Congress.

"Our discussions with the Office of Management and Budget are ongoing," Ms. Lopatto said.

Critics of the Energy Department have argued that it is not prepared for attacks by suicidal terrorists, a threat not obvious before Sept. 11.

For example, the critics say, terrorists might enter areas where uranium or plutonium from bombs is stored, and rather than try to flee with material, giving defenders a chance to intercept them, they could assemble a bomb on the spot and cause a nuclear explosion. They could also enter with explosives and blow up a tank of nuclear waste, critics say, releasing vast amounts of radioactive material to spread with the wind.

David J. Sirota, a spokesman for the Democratic minority on the House Appropriations Committee, said the $138.3 million requested to protect storage of nuclear weapons and materials and the $100.8 million for security at nuclear weapon cleanup sites were worth providing.

Mr. Sirota asked: "Should we give Enron executives the $250 million tax break President Bush proposed, or should we use that money to secure our country against a nuclear attack using our own nuclear materials?"

The committee's ranking Democrat, David R. Obey, of Wisconsin, sought more money for nuclear weapons security in November but was voted down on party lines in committee in November, and the House voted, 216 to 211, not to debate the idea.