Leaders of Roman Catholic, Protestant and Jewish organizations joined with civil rights, human rights and Haitian groups yesterday in a national coalition to demand the immediate release of 2,100 Haitian refugees, and called for a congressional inquiry into the administration's detention policy.

The Haitians, Creole-speaking blacks, have been detained for up to 10 months in federal prisons and immigration centers in South Florida, Kentucky, Texas, Puerto Rico, New York and West Virginia awaiting deportation hearings by the Immigration and Naturalization Service.

Detention of all Haitians entering the country illegally began last May. Until then, immigrants were routinely released, usually in South Florida, but that policy changed when Florida officials began to complain.

At a Capitol Hill news conference, Bishop Anthony J. Bevilacqua of the National Conference of Catholic Bishops said religious groups stand ready to sponsor the Haitians and guarantee their appearance at legal hearings. Their "indefinite imprisonment" is "an act of discrimination which violates their rights of due process...and the principles of justice and compassion for which this nation stands," he said.

A U.S. District Court judge in New York recently upheld that opinion when he ordered the release of Haitians being detained in Brooklyn, saying they were singled out for detention. The administration is appealing.

"Race is undoubtedly a factor in the treatment of the Haitians," Wade Henderson of the American Civil Liberties Union said. "Why else are Haitians the only nationality being detained by the United States as a matter of policy while their political asylum claims are being determined?"

David Hiller, associate deputy U.S. attorney general, said yesterday that the Reagan administration had asserted the new detention policy in order to enforce the law, which, he said, requires imprisonment of illegal aliens until their status is determined.

Under previous administrations, he said, "The whole system had broken down. The United States was running an open-ended immigration program. People coming in were turned loose."

Until the Reagan administration changed policies, most of the Hai-tians, like the Cubans and Indochinese who have come here in far greater numbers, were allowed to blend into the community until their status was resolved.

Coalition members said the Haitians are suffering from a number of health problems, including depression, and that since their arrival, about 130 of the male prisoners have contracted gynocomastia, a rare hormonal disease which causes enlargement of the breasts. This month, a group of Haitian women detained at a federal prison in Alderson, W.Va., charged that they are being denied access to medical care and a decent diet and staged a hunger strike to dramatize their plight. Another group of women is staging a hunger strike in Miami.

Brian Dugan, refugee coordinator for the Center for Disease Control, said doctors there have studied the gynocomastia problem since December and "to date we haven't found the cause." Church groups complained yesterday that the victims have not been allowed to see private doctors.

The Coast Guard's policy of turning back Haitian refugee boats was sharply criticized by Rabbi Marc Tanenbaum of the American Jewish Committee, who said he witnessed the drowning of a boatload of about nine Haitians about 50 yards off the Florida coast last year after they were turned back by a Coast Guard vessel.

Hiller said he was "shocked" to hear of the incident from a reporter and called it "entirely apocryphal" since the interdiction is supposed to occur only off Haitian shores.

Participants in the press conference also included Bayard Rustin of the A. Phillip Randolph Institute, Reps. Shirley Chisholm (D-N.Y.) and William Gray (D-Pa.) and representatives of the National Council of Churches, the Lawyers Committee for International Human Rights, and the Lutheran Immigration and Refugee Service.