The Immigration and Naturalization Service yesterday reversed a stance that had drawn strong protests from Hispanic and human-rights groups by announcing a new policy to prevent the deportation of as many as 100,000 illegal aliens who are the children and spouses of newly legalized immigrants.

The new "family fairness" guidelines announced by INS Commissioner Gene McNary represent a potentially significant modification to the amnesty program created by the 1986 Immigration Reform and Control Act. That program has provided amnesty to up to 3 million illegal immigrants who entered the country before Jan. 1, 1982.

Under the new policy, children and spouses of those newly legal immigrants will be granted a temporary status that will permit them to receive work permits and protect them from deportations. However, it will apply only to illegal immigrants who have been residing here since Nov. 6, 1986, when the amnesty program took effect.

The prospect of widespread deportations of children and spouses had become one of the most emotional and pressing issues within immigrant communities in recent years, according to spokesmen for Hispanic groups.

During the massive waves of illegal immigration in the 1980s, illegal aliens, mostly men, came to the United States to seek jobs, leaving their families behind. While many of them were granted amnesty, their spouses and children who later followed them, arriving after the 1982 amnesty cutoff date, were considered illegal aliens and technically were subject to deportation.

Earlier "family fairness" guidelines used by the INS barred deportations for "compelling humanitarian reasons." But critics charged that those rules were applied inconsistently or were ignored, prompting warnings from immigrant and human-rights groups of a "massive human tragedy" if the INS began breaking up families with deportations.

"This may be a turning point for INS," said Cecilia Munoz, a policy analyst for the National Council of La Raza, a group that has sharply criticized the INS in recent years. "After years of stonewalling, the Immigration Service has responded to this emerging human tragedy with compassion and fairness."

La Raza and other Hispanic and human-rights groups had lobbied to change INS policy, highlighting cases such as one last month in Texas where the INS was threatening to separate a 3-year-old boy from his mother by deporting him to Mexico. "The INS does not look particularly good when it gets front-page coverage in newspapers that it is deporting young children," said Munoz.

She noted, however, that the new policy "does not cover everyone" and that children over the age of 18 and family members who arrived after Nov. 6, 1986, still may be subject to deportation.

But a spokesman for the Federation of American Immigration Reform, a group that has lobbied to curtail illegal immigration, attacked the modification as too lenient and charged that it would encourage thousands of people to enter the United States illegally.

"We are shocked by the announcement," said Dave Ray, a federation spokesman. "This will serve as nothing more than a magnet for persons waiting in other countries to illegally enter the United Stations . . . . They will see this as a rolling amnesty, an incentive to come north, duck down for a couple of years and wait for another amnesty."

Ray added that the INS might as well have given the affected aliens permanent legal status. "The reality is people never leave," he said. "You might as well call them immigrants."

McNary said yesterday that few family members of individuals granted amnesty under the 1986 immigration reform law had been deported. But he acknowledged that the old policy on deportations of family members had been too "nebulous" and had not been "evenly and uniformly enforced."

Moreover, he said, "to split families simply encourages further violation of the law as they {illegal aliens} attempt to reunite."

The new status for which family members will qualify is "voluntary departure," a category widely granted to Poles, Afghans and other political refugees fleeing communist regimes.

INS law envisions it as a transitional state, permitting persons to work in the United States without being eligible to become permanent residents.

But as a practical matter, some experts said, those affected by the new policy eventually will qualify to become fully legal immigrants. For example, a spouse or parent who becomes a permanent resident can apply to have family members granted permanent legal status.

McNary said the cases of those granted voluntary departure will be reviewed annually by the INS to determine whether the aliens have committed crimes or have become dependent on public assistance. Aliens could be deported if they commit crimes or if they become "public charges," he said.