The Reagan administration has been "deceptive and harmful" in depicting the human rights situation in Nicaragua to the point of "debasement" of the human rights cause worldwide, Americas Watch said yesterday.

Releasing a report comparing Reagan administration and Nicaraguan government statements with its own research, the New York-based human rights group charged that, although there is "a core of fact" of human rights abuses in Nicaragua, "around the core of fact, U.S. officials have built an edifice of innuendo and exaggeration."

The report, titled "Human Rights in Nicaragua: Reagan, Rhetoric and Reality," said President Reagan has wrongly charged Nicaragua with being a "totalitarian dungeon," of persecuting church groups and of waging genocide against native Miskito Indians.

Data in press releases and in regular State Department reports on human rights has been misleading and misused in an effort to build support for ousting the leftist Sandinista government of Nicaragua, the report said.

"Such a concerted campaign to use human rights in justifying military action is without precedent in U.S.-Latin American relations, and its effect is an unprecedented debasement of the human rights cause," the report said.

"The Nicaraguan government must be held to account for abuses which continue to take place, like restrictions on press freedom and due process. But unless those abuses are fairly described, the debate on Nicaragua ceases to have meaning."

State Department officials said they would have no comment until they read the report, but some Reagan administration officials have previously criticized Americas Watch as a leftist group whose reporting is politically biased.

Americas Watch, affiliated with the Helsinki Watch Committee, is backed by the Fund for Free Expression and the MacArthur Foundation. This report is the eighth it has issued about Nicaragua since 1982.

The 89-page study said that "clear abuses" by the Sandinistas were perpetrated against some Roman Catholic Church priests but that "the issue of religious persecution in Nicaragua is without substance."

Although the Miskitos "suffered serious abuses in 1981 and 1982" as they were being forcibly relocated, and some cases of missing Miskitos remain unresolved, the government's record "has improved dramatically" since then, the report said.

The sole remaining opposition newspaper, La Prensa, "suffers heavy-handed prior censorship" but continues to publish, the report said. It noted that some business and labor leaders had been jailed for peaceful activities, 10 priests have been expelled and political parties have generally not been allowed to hold rallies.

"Perhaps most disturbing of all," the report said, "there has been an interlocking relationship between the Sandinista party and the state."

However, "the most violent abuses of human rights in Nicaragua today are being committed by the contras," the antigovernment rebels fighting the Sandinistas with U.S. support, and "the Reagan administration's policy of support for the contras is, therefore, a policy clearly inimical to human rights," the study said.