A group of clerics and lay workers, including a Presbyterian minister, two Catholic priests and three nuns, appeared before federal magistrates in Tucson and Phoenix this week to plead not guilty to charges stemming from their operation of an "underground railroad" to smuggle Central American refugees into the United States.

As a handful of Salvadorans wearing bandanas as masks hovered outside the federal court building in Tucson on Wednesday, six defendants were told they would get court-appointed attorneys and then formally denied their guilt before federal Magistrate Raymond T. Terlizzi.

A seventh defendant will be arraigned in a week, after she hires a lawyer. She has said she will plead not guilty at that time.

Later Wednesday, the Rev. John Fife of Tucson's Southside Presbyterian Church and his six codefendants denounced the federal charges against them and vowed to continue "to be open in the practice of our sanctuary ministry."

Citing international law established by the Geneva Convention of 1949, Fife insisted that he and his colleagues have obeyed a provision that "when the government fails to protect refugees, civilians have the legal right to do it themselves."

Under that doctrine and the U.S. Refugee Act of 1980, he added that "it is the United States government that is violating the law."

Earlier in the morning, six defendants in Phoenix pleaded not guilty in federal court after a mass prayer meeting at St. Mary's Catholic Church and a procession to the court building.

When the undercover agents had finished their 10-month investigation, 16 people, including Fife, were indicted on 71 counts of conspiracy to smuggle illegal aliens into the United States and related charges. Each of the offenses is punishable by up to five years in prison and fines of up to $10,000.

Twenty-five other people, some from churches in Pennsylvania, Vermont and Washington state, were named as unindicted coconspirators along with 60 aliens, who were arrested one week after their smugglers but were not indicted.

There is a fear now among the coconspirators that they will be asked to testify against the principals in the case. One unindicted coconspirator from Seattle said he had been advised to "refuse to testify on the grounds of self-incrimination and religious freedom. He expects others to do the same if called to the stand, he said.

But sanctuary workers worry that the aliens, who have no such rights, may be offered the choice of testifying in exchange for asylum. If they refuse, they would face deportation to Central America, where, sanctuary workers say, the refugees would face torture or murder.

Msgr. Daniel F. Hoye, general secretary of the United States Catholic Conference, expressed regrets that the government's Central American policies have created circumstances that "entangle people of good faith in criminal prosecutions."

Hoye and national heads of three Lutheran denominations called for a policy of extended voluntary departure for refugees from Central American turmoil.

Officials of the U.S. attorney's office and the Immigration and Naturalization Service contend that illegal aliens smuggled into the United States by sanctuary workers are merely interested in economic asylum. Their fears about political persecution, say the federal spokesmen, have not been proved.

As for the indicted sanctuary workers, their argument that smuggling refugees is an exercise of religious freedom already has come under fire in a pretrial hearing for an indicted sanctuary worker in Texas.

A federal judge there ruled this week that the need to enforce immigration law takes priority over the sanctuary worker's right to religious freedom.

All of the Arizona defendants and unindicted coconspirators have been allowed to remain free until their court dates.

The Tucson defendants, except for Katherine Flaherty, are scheduled to appear for trial April 2 in U.S. District Court in Phoenix. Flaherty will be arraigned next Wednesday.

Seven aliens arrested in Seattle also are free until deportation hearings are scheduled.