U.S. military helicopters ferried hundreds of Honduran soldiers today to an area near the Nicaraguan border where Nicaraguan troops entered the country to attack anti-Sandinista rebels, U.S. officials said.

The helicopters landed at least nine miles away from the scene of any combat to avoid placing the approximately 50 U.S. pilots and crew members in danger, the officials said.

The Honduran armed forces held a news conference at which two men identified as Nicaraguan soldiers said they had been captured inside Honduras.

Forces of Nicaragua's Popular Sandinista Army reportedly were continuing their two-day-old withdrawal, and the Honduran Army indicated that it was seeking to make a show of force with U.S. backing rather than to drive out the Nicaraguans.

Honduran armed forces spokesman Maj. Napoleon Santos said the Hondurans adopted "defensive positions" and "definitely are not chasing the Sandinista troops."

The anti-Sandinista rebels, known as contras or counterrevolutionaries, were harassing the Nicaraguans as they pulled back through the heavily forested mountains, but the level of fighting remained low for a second day after heavy combat on Sunday and Monday, well-placed sources said. The sources spoke on condition that they not be identified by name or nationality.

Several Honduran reporters and a U.S. television crew succeeded in entering the border area in eastern El Paraiso province, and they quoted residents as saying heavy fighting had taken place inside Honduras Sunday and Monday between the Sandinistas and the contras. This was the first independent confirmation of the fighting, which at first was reported only by U.S. sources. The Honduran government later confirmed the reports.

The two captured Nicaraguan soldiers gave brief statements at the news conference saying that they had been captured Monday nine miles inside Honduran territory. The armed forces also displayed diaries and other documents that it said were taken from theseand other prisoners, and highlighted in yellow ink passages recording various incursions inside Honduras by Nicaraguan units in January, February and in recent days.

The prisoners identified themselves as Mario Hernandez and Carlos Sandino, and said they belonged to the Francisco Estrada Battalion of the Nicaraguan Army. Sandino was wounded in the chest and the right leg, and Hernandez was accompanying him. Honduran officers said the two were captured because Sandino's wound had slowed them down.

The prisoners were not allowed to answer questions. In statements that appeared to have been rehearsed, they said they were captured by the Honduran Army's 7th Battalion. But informed sources said the contras had captured them.

The use of the 14 U.S. military helicopters to transport Honduran troops for combat purposes marked an escalation in U.S. military involvement in Honduras. Thousands of U.S. troops and National Guardsmen have staged maneuvers here since 1982 in a U.S. effort to train U.S. and Honduran troops and intimidate Nicaragua's revolutionary Sandinista government.

Until now U.S. forces had not been directly involved in a military operation.

The U.S. government said that the stepped-up involvement was necessary to respond to what it described as the largest cross-border raid ever staged by Nicaraguan troops.

But the U.S. version of events here contrasted with the Honduran government's reluctance in the past two days to make a major issue of the incursion.

The Americans had to "convince" the Hondurans that the matter was serious because the government here was wary of getting involved in a clash between Nicaragua and the contras, according to two well-placed sources.

Two Honduran officials said yesterday Washington had played up the reports of the raid to influence Congress to approve $100 million of U.S. aid to the contras.

The Honduran government declined again today to say how many Nicaraguan troops had entered the country.

Nicaragua, which has consistently denied having sent troops across the border, challenged the United States and Honduras by asking the Contadora group to establish a border commission to find the Sandinista troops in Honduras and to stop contra raids on Nicaraguan territory, The Associated Press reported.

One knowledgeable source who declined to be identified said that the "maximum" number of Nicaraguan troops involved in the incursion was only 800. The official U.S. version is that 1,500 Nicaraguan soldiers crossed the border late Saturday, and sought to take a contra training center approximately 10 miles inside Honduras and a base camp somewhat closer to the border.

In addition, the Honduran government waited until yesterday morning to confirm that an incursion had even taken place, and did so only after the U.S. government had publicized the incursion in Washington.

The Honduran armed forces issued a communique this afternoon saying that it had delayed making public the information about the incursion for "obvious reasons" in order "to maintain the calm and tranquility of the people in this period of rest."

This is Holy Week, an important holiday in this Roman Catholic country, and the mood in the capital was relaxed in spite of the joint U.S.-Honduran military operation. Government offices closed at midday and were not to reopen until Monday, and President Jose Azcona went on vacation away from the capital yesterday.

Ten UH1H (Huey) helicopters and four CH47 (Chinook) helicopters began early this morning to transport Honduran troops from an Army base near the capital to the border area. They were expected to finish the airlift of between 500 and 600 Honduran infantrymen, with artillery, by dusk.

The helicopters carried the Hondurans first to a dirt airstrip, constructed two years ago by U.S. military engineers, at Jamastran, 12 miles east of the southern city of Danli. Then the troops were ferried to a hamlet called Capire, six miles north of the border town of Las Trojes.

Washington Post staff writer Lou Cannon reported the following from Washington:

White House spokesman Larry Speakes said at the regular noon briefing that "in addition" to the 1,500 Sandinista troops that he said had attacked across the Honduran border, "additional Sandinista forces" have occupied the area of San Andreas de Bocay to the east.

He also said the administration had received confirmation that Soviet-made MI8 helicopters have been providing fire support for Sandinista operations in Honduras