An article Saturday incorrectly attributed to President Reagan a statement calling Iranian Prime Minister Mir Hossein Mousavi a "kingpin in the Iranian terrorist operation." It was made by an administration official.

Iranian Prime Minister Mir Hossein Mousavi declared his support for Nicaragua's Sandinista government today but sharply denied Reagan administration charges that his country is supporting international terrorism or supplying the Sandinistas with arms.

"We deny any support for terrorism," Mousavi said, speaking through an interpreter at an airport press conference before ending his two-day visit.

"These two revolutions," he said, referring to both the Nicaraguan and Iranian governments, "have made the interests of the United States disappear in their parts of the world. That is why it is natural that we are the targets of these accusations."

Yesterday, Reagan accused Mousavi of being "a kingpin in the Iranian terrorist operation." Reagan, speaking before a conference of legislators from around the Western Hemisphere, said the interests of Iran, Libya and the Palestine Liberation Organization in Nicaragua represented "a new danger in Central America."

The Reagan administration already is insisting that the Sandinistas reduce their ties to the Soviet Union, which has supplied them with arms, and to Cuba, which has provided hundreds of military advisers. It has accused those countries of fostering terrorism in Central America, working through the Sandinistas, and has supported the Nicaraguan rebel war for three years against the leftist government.

But western diplomats said Iran is playing a minor role in Nicaragua and is not known to have either military or internal security personnel in the country as do the Cubans.

Mousavi denied charges made by the Reagan administration that Iran is sending arms to the Sandinistas. "I am very astonished to hear about the arms dealing," he said. "There is nothing like that here."

"I am surprised," he added, "because the United States is sending arms to all the arrogant nations of the world, those that oppress revolutions, and no one says anything."

One western diplomat said there had been rumors that Iran might be supplying "small arms," but he said there was no proof that those allegations were true.

The same diplomat said the Iranians had "been keeping a very low profile" in diplomatic circles.

There have been a number of contacts between dignitaries from Libya and Iran and Nicaragua in the past year. Musa Ahmad Abu Furaywah, the Libyan minister of economy and light industries, and Nicaraguan Trade Minister Alejandro Martinez Cuenca signed a $15 million agreement to exchange coffee, bananas and other agricultural products for oil earlier this month, according to reports from the Spanish news agency EFE.

In December, the Iranian news agency reported that Iran's ambassador in Managua and Martinez discussed political and economic ties.

Last March, Sergio Ramirez, now vice president of Nicaragua, visited Iran, and officials later announced that the two governments had reached a trade agreement for about $23 million.

In Washington earlier Friday, Robert Sims, a deputy White House press secretary, said the Reagan administration believed Iran was "in the process of arranging support in the form of oil supplies and funding for armaments which would add to the Nicaraguan arsenal," The Associated Press reported.

Sims said Mousavi's visit to Nicaragua "is obviously evidence of political support" and that "the potential for some exporting of terrorism in this hemisphere is also a matter of concern."

Asked about oil shipments to Nicaragua, Mousavi said, "In previous years, Nicaragua was purchasing oil from the Islamic Republic of Iran like other countries. This year there were no talks on new purchases in this regard."

According to official records of the Nicaraguan Foreign Ministry, there are three Iranian diplomats serving in Nicaragua. Mousavi insisted that those three are the only Iranian diplomats in the country.

According to the same Foreign Ministry records, the Soviet Embassy has 20 diplomats, the United States 16, Cuba 14, Libya four and the PLO's diplomatic mission three.

The Soviets are thought to have about 200 persons working with the Nicaraguan government, many of them doctors and technicians. The Soviet Union replaced Mexico this year as the principal supplier of oil to Nicaragua.

Other Warsaw Pact nations, notably East Germany, are believed to have substantially closer ties to Nicaragua than Iran, Libya or the PLO. East Germany, for instance, has supplied hundreds of military trucks to the Sandinista government.

The Cubans are known to have thousands of "internationalists" in Nicaragua, including military advisers, teachers and doctors.

There have been strong rumors in diplomatic circles of PLO military advisers, although there has been no definitive proof. The Libyans, diplomats say, have made considerable investments in Nicaraguan agricultural projects.

"There are the official lists and then there are the other people, and it is not clear who they are," said one European diplomat, "but the Iranians -- they have a very moderate interest here."

Nicaraguan President Daniel Ortega, who saw Mousavi off at the airport, accused the Reagan administration of trying to make a "scandal out of the visit of the prime minister of Iran."