The Vatican has forbidden Brazilian Bishop Helder Pessoa Camara, a perennial nominee for the Nobel Peace Prize, to travel abroad, according to the weekly National Catholic Reporter published today.

Reasons for the ban, which went into effect late last year, could not be learned since Helder Camara has declined to answer questions on the matter, the Kansas City-based weekly says.

Helder Camara is archbishop of Recife in Brazil's poverty-stricken Northeast. He has gained the emnity of military-dominated government for his outspoken defense of human rights and denunciation of living conditions among the poor.

Since the government placed a virtual ban on all press coverage of Camera early a decade ago, he has turned increasingly to speaking engagements in Europe and North America to criticize human rights violations both in Brazil and elsewhere.

Brazilian conservatives call him the"Red Bishop" for his attacks on capitalism as the source of much of the Third World' economic woes. He has sharply criticized the Soviet Union as well.

Last summer, the prelate was awarded an honorary degree by the University of Notre Dame, along with President Carter.

Disclosure of the Vatican restriction on the archbishop came only a week after the National Catholic Reporter revealed another unusually harsh Vatican effort to stop a human rights program that had the backing of the entire conference of bishops in Brazil.

That project, the International Study for a Society Overcoming Domination, was launched by the Brazilian bishops in 1975 and involved church groups in nearly 90 countries, including the United States.

The objectives were to study "oppressive systems and explore alternatives for achieving a more just social order," and to denounce "violations of human rights and the structures that makes them possible," according to the weekly.

One person familiar with the project called it a "modest educational process," designed to encourage groups to study their own situation and search out the "structures" - political, economic or otherwise - that get in the way of human rights.

The project evolved out of a document adopted by the Brazilian bishops in 1973. To advance their continuing struggle with military government, they used the 25th anniversary of the U.N. Declaration on Human Rights to spotlight the issue with a widely publicized statement that asserted the church's responsibility to fight for human rights.

The project took on international proportions, with a secretariat in both Brazil and in Paris and with funds coming from church groups in several countries, including the United States and Canada.

The Catholic Reporter speculated, and others familiar with international project may have been a threat to tra-church politics have agreed, that the international dimensions of the Brazil ditional Vatican international relations. Vatican diplomats met with the program's planners in Brazilia in January.

The Catholic Reporter, a lay-edited weekly, charges that two U.S. bishops, the Most Rev. James Malone of Youngstown, Ohio, and the Most Rev. Raymond Lessard of Savannah Ga., were enlisted by the Vatican to attend the January meeting in Brasilia and bring pressure to curtail the rights study project. Neither bishop could be contacted yesterday for comment.

The human rights study project appears to have survived the meeting but in a curtailed fashion the Brazilian bishops' conference, which meets next month, is expected to drop its affiliation with the effort.

The curtailment of Camara's travel and Vatican pressure on the human rights study do not appear to be immediately related, since Camara has not been closely associated with the study project.

The National Catholic Reporter, which has built much of its reputation on its willingness of criticize the Church establishment, sees these events as a momentary triumph for conservative forces at the Vatican, however. While acknowledging that the Camara travel ban came from Pope Paul VI, the paper suggests that the pontiff "was being used."

Other long-time observers of international Catholic politics suggest that the Vatican itself may be feeling the pressure of the Brazilian government to force that country's bishops to moderate their activities.

The events in Brazil come at a time of heightened controversy over the Latin American church.