A Reagan administration official charged yesterday that Cuban troops have taken a combat role in Nicaragua, fighting with Nicaraguan armed forces against U.S.-backed rebels.

Assistant Secretary of State for Inter-American Affairs Elliott Abrams Jr. said he has received "more and more reports" of Cuban military action as part of "a massive Soviet and Cuban intervention" in Central America.

"We may be seeing Cubans move into a combat role on the mainland of North America," he told the House Foreign Affairs subcommittee on Western Hemisphere affairs. Later, he said Congress ought to renew military aid to the rebels, or contras, "or we are going to be seeing a Soviet base in Nicaragua."

Abrams said about 2,500 Cuban military personnel are in Nicaragua acting as advisers "down to very small units of the Nicaraguan army." Last year, the administration put the number of Cubans in Nicaragua at 3,000 military advisers and 6,000 Cuban teachers and construction workers. Abrams also said Cubans "were among the casualties" when the contras, using a Soviet SA7 surface-to-air missile, shot down a government helicopter in northeast Nicaragua Monday.

Other State Department officials said evidence for the expanded Cuban role came from intelligence reports and sightings by contra troops.

Last night, the Nicaraguan government charged that the Reagan administration has brought the Central American conflict to "previously unknown levels" by providing the rebels with antiaircraft missiles, Washington Post correspondent Edward Cody reported.

[Deputy Foreign Minister Victor Hugo Tinoco announced that Nicaragua was recalling its ambassador in Washington for consultations and seeking a meeting of the U.N. Security Council to protest what he called "a new step" in U.S. support for rebel forces.]

A Nicaraguan Embassy political officer here denied that Cubans are fighting in Nicaragua and said Abrams was "making it up" about Cuban casualties in the helicopter incident. A defense ministry communique Tuesday said 14 persons died in the crash of a Soviet Mi8 transport helicopter but denied that Cubans were aboard.

Manuel Cordero of the Nicaraguan Embassy said warnings about a Soviet military base are "an attempt to raise the Soviet-Cuban specter to scare Congress into funding the contra program." He said 700 to 800 Cuban military advisers are in Nicaragua and described them as "not enough to be involved with small units."

Subcommittee Chairman Michael D. Barnes (D-Md.) released the text of a letter from the General Accounting Office on its unsuccessful efforts to meet with State Department officials for an audit of the $27 million program of humanitarian aid approved by Congress last summer for the contras.

Abrams said some of the program involves classified material not authorized for release to the GAO. He also refused to discuss publicly the reported halt in aid shipments to the contras' bases in Honduras, which does not formally recognize their presence.

"That is an inappropriate question," Abrams said. "If this program is unpleasing to you, it's not exactly the greatest program in the world from our point of view either," he said. The administration has argued that the overt aid program is almost unworkably complicated as dictated by Congress.

Asked whether trucks supplied under the humanitarian aid program could be used to transport weapons, he said that there is "absolutely no prohibition on the use of those trucks" in the law but that he had asked the House and Senate intelligence committees to advise him on the matter.

Abrams also acknowledged that the contras have committed human rights abuses but said they "are really beginning to deal with them now in a very serious way."

Later, he told a House Banking, Finance and Urban Affairs subcommittee that "the ice is cracking a little bit" in the Chilean human rights situation.

He responded sharply to Democrats' charges that he has been soft on Chile and has ignored the law in failing to notify Congress of renewed U.S. support for international bank loans to Chile.

"This is a strange hearing," Abrams said. "These are the same damn accusations" the administration received regarding its loan policy toward Argentina, which subsequently became democratic, he said. "The purpose of the policy is not to express outrage but to achieve change."