Nicaragua's defense minister left this week on an arms buying trip to seven or eight European and Latin American countries, including Cuba, the commander-in-chief of the new Sandinista Popular Army said today.

Commander Humberto Ortega also announced at a press conference that Nicaragua's armed forced will send its own delegation to the conference of nonaligned nations, now meeting in Havana, to confer with leaders of some of the nearly 100 Third World countries represented there.

Ortega implied that the Nicaraguan delegation will request military assistance from these countries in addition to the arms Nicaragua has already sought from industrialized countries.

Although Ortega restated his government's hope that the United States will be a primary source of military assistance to Nicaragua's fledgling armed forces, he also said that this country is determined to secure enough arms to defend itself properly and will obtain them from sources outside the United States and Western Europe if necessary.

The announcement that Defense Minister Bernardino Larios will visit Cuba on his current trip, and Ortega's strong reaffirmation that Nicaragua believes it needs additional but unspecified quantitites of modern weapons, came shortly after La Prensa, the country's most important newspaper, today published a frontpage story from Washington saying that the Carter administration had indicated that it would prefer not to supply Nicaragua with arms.

The Agence France-Presse story, which was denied by the U.S. Embassy here, quoted State Department sources as saying that the administration would prefer to concentrate its efforts on winning congressional approval for a large economic assistance package rather than complicating that issue by requesting permission to supply Nicaragua with military aid as well.

Whether the United States decides to provide Nicaragua's new revolutionary government with military assistance or not, Larios' trip indicates that the government here is determined to seek arms from other sources and is not disposed to wait until Washington makes a decision.

Ortega said Larios will visit Cuba, West Germany, Belgium, Spain, Mexico, Brazil and possibly one or two other countries before he returns here next week.

Larios' stop in Cuba is the latest in a growing series of contacts and agreements between Nicaragua and the Government of Fidel Castro in Havana. Earlier this week, the two countries reached agreement on a wide-ranging educational exchange program to begin next month. Cuba already has about 75 doctors and medical technicians here.

The latest agreement provides that 650 students between the ages of 12 and 18 will be sent to Cuba to study at a special high school on the Island of Youth. Havana will pay all of the students' expenses and will allow them to continue their education through the university if they choose to stay.

In addition, 90 Nicaraguan soldiers will be sent to study in Cuba, according to the published text of the accord.

Meanwhile, Cuba has agreed to send between 500 and 1,000 teachers to Nicaragua to teach in rural elementary schools for a period of two years. The Cuban government has agreed to pay these teachers' salaries and the cost of their transportation, while the Nicaraguan government will provide housing and food, according to the agreement.

Cuba also has agreed to send advisers to help the Ministry of Education here develop new curricula for the public-school system and plan a campaign against illiteracy. It is estimated that about 70 percent of Nicaragua's 2.5 million people are either totally or functionally iliterate.

Cuba will also send 30 to 40 visiting professors to teach in Nicaragua's universities when they reopen Sept 17, and will give scholarships to 40 Nicaraguan university students to study in Cuba. The Cubans have also promised to set up a post graduate program for Nicaraguan students in Cuban universities.

While the United States has so far provided the bulk of the food and medical aid received by Nicaragua since the country's devastating civil war ended July 20, U.S. diplomats here have said that Washington has not yet been able to offer technical or educational assistance on a long-term basis because of bureaucratic and budgetary restrictions.

In addition to the medical technicians Cuba has already sent and the teachers and other advisers it will soon have here, both Mexico and France have sent teams of doctors to work in Nicaragua's hospital. Panama has sent military and police experts to begin training this country's new national police and armed forces.