Kidnaped Youths Returned to U.S. Mother : Balkans: She never gave up hope. Children are found in Yugoslavia 6 years after Serbian father lost custody.

An American woman who had been fighting for six years to regain her two children, spirited away and hidden by her Serbian ex-husband, took them home Saturday after a secret raid engineered by authorities here.

U.S. Embassy officials said that Shayna Lazarevich, whose custody battle had been fought in the halls of Congress and the office of Serbian President Slobodan Milosevic, left here early Saturday with her young son and daughter on a flight for San Francisco.

Authorities found the children by acting on a tip from a man who had watched a documentary about them on state-run television Monday. Milosevic, deep in negotiations with U.S. officials over the continuing war in neighboring Bosnia-Herzegovina, was personally involved in securing the children and handing them over to American authorities, embassy officials said.

“There was mysterious and surprisingly fast reaction” from Milosevic, who three years ago had assured Lazarevich that he could quickly resolve the situation and then did little as she pleaded with Serbian courts and police to enforce her custody rights, a diplomatic source said.

Milosevic’s cooperation last week came after talks about the possible lifting of international economic sanctions against this country broke off without agreement.

Lazarevich, from Santa Cruz, spent the past six years and tens of thousands of dollars trying to get her children back to American soil. Now 33, Lazarevich won custody of her children after she and her husband, Dragisa, divorced in 1989. But Dragisa Lazarevich, an arms and machinery manufacturer in California, kidnaped the children during a weekend visit later that year and took them to Serbia.

Over the years, both California and Serbian courts ruled that Shayna Lazarevich should have exclusive custody of the children. But her husband flouted the law, and no authority here would force him to turn over the children.

Lazarevich, a regents scholar at the University of California, campaigned through congressional offices and crisscrossed the Atlantic to find the youngsters. The last U.S. ambassador here, Warren Zimmermann, pressed the case with the Serbian justice minister. In 1991, James A. Baker III, then secretary of state, met with Milosevic and told him that the U.S. government considered the Lazarevich case a serious miscarriage of justice.

Their arguments went ignored.

“She never gave up,” Lazarevich’s father, Stanley Gluck, said in a telephone interview from his home in Binghamton, N.Y. “Those are her children, and she bore them, she nursed them, and there was no way she was going to give them up.”

Embassy officials were tipped off to the whereabouts of Sasha and Andre Lazarevich, now 12 and 9, after last week’s nationwide documentary broadcast. Dozens of sympathetic Serbs called Belgrade television to complain about Lazarevich’s plight, embassy officials said.

One caller, from the northwestern town of Subotica, said he recognized pictures of the children as classmates of his grandchildren. The man knew the children as Sonja and Darko Lazarov, Gluck said.

Gluck said embassy officials and police in Subotica consulted. Lazarevich’s former husband was detained as police raided his two-bedroom apartment in the small town near the Hungarian border and took the children, he said.

The children were taken to Yugoslav authorities and Milosevic called the U.S. Embassy with the news, embassy officials said. Lazarevich, contacted Thursday, flew to Belgrade and was reunited with the children Friday, her father said.

That same day, however, her former husband apparently attempted to gain entry to the embassy, where the mother and children were in safekeeping. He asked for a U.S. visa, which was refused, an embassy official said.

“It’s still a fearful situation,” Gluck said. “I was hoping he’d spend a long, long time in jail. I was shocked that he was free before she was out of the country.”

Gluck said that Dragisa Lazarevich’s Yugoslav passport has been confiscated by authorities here, but the family worries that the man, who an embassy source said has been arrested for carrying false passports, could find a way to return to the United States to take the children.

“We know he travels a lot and he deals in arms and industrial machinery. . . . There’s always a fear he could figure out something,” Gluck said.