The Reagan administration has denied all foreign officials permission to attend a major conference here next week on the commercial applications of superconductivity.

The decision has enraged American scientists as well as the European and Japanese embassy officers who have been told they cannot attend. Since the discovery last year of high temperature superconductors, which carry electricity without losing energy to resistance, scientists from around the world have worked intensely to develop the commercial potential of the new materials.

"This has been an international project from the start," said Robert Parks, director of the Washington office of the American Physical Society. "The openness here has been just astonishing. That is why the advances have come so fast. If we start closing the doors now, the United States stands to be a very big loser."

The conference, sponsored by the White House and the Department of Energy, will bring together representatives from U.S. business, government, universities and laboratories to discuss research. President Reagan is scheduled to speak at the conference on Tuesday, the first day of the meeting.

The decision to close the conference to all but Americans was made by the president's science adviser, William R. Graham Jr., over the objections of members of his staff, according to administration sources.

"We wanted to have a domestic forum where we could talk to our own industry, our own corporate structure and our own universities and labs," Graham said on why foreign representatives are barred.

More than 1,000 people are expected to attend the conference, which will be open to the news media, both domestic and foreign. The conference will not focus on advances in basic research, and no new scientific information is expected to emerge.

Speeches about American competitiveness have gained great currency on Capitol Hill this session. And many in government have seized on the development of the new superconductors as an essential chance for America to beat Japan to the marketplace.

"Major applications are years away," said one embassy's science officer after he was denied permission to attend the conference. "Why is America trying to prevent people from attending a conference like this? It is a petty thing to do."

Embassy officials interviewed requested that their names not be disclosed. But they were angry about the decision, and they contrasted the administration move with the international flavor of recent research.

The new materials were discovered in Zurich, for example, and the findings were first confirmed in Japan. Much of the best U.S. work has been carried out at the University of Houston by Paul Chu, a Chinese American. A recent scientific conference on the materials, held in Berkeley, Calif., resembled a scientific United Nations.

"It would be a shame to lessen the flow of information," Chu said in an interview. "In the long run, everybody would lose by that."

He said that while he did not understand the decision, it was unlikely to matter since the conference will concentrate more on communication among companies, universities and the government than on research.

As scientists learn how to manipulate and manufacture the new ceramic materials, businesses are thinking more seriously about how to adapt commercial applications. Japan has established a consortium of business and government officials to help steer its national efforts. The Japanese reportedly are almost ready to introduce a magnetic resonance imaging device using the new materials. The devices are used by hospitals to examine the body through measuring its sensitive magnetic fields.

In the past, superconductors could be found only at extremely low temperatures, making them costly and cumbersome. But the new superconductors have brought many uses, including electronics and computers, within reach.

If materials can be found that act as superconductors at room temperature, they could revolutionize the storage and generation of electrical power.