WASHINGTON, D.C. — Jewish activists are urging President Clinton to veto the welfare reform bills approved by Congress, saying the legislation threatens the nation's poor and relegates immigrants to second-class citizenship.

A House-Senate conference committee must reconcile the Senate version, passed last week, with an earlier House bill.

Jewish activists are blasting most of the Senate bill, including its five-year limit on benefits, the lack of adequate child care provisions, the denial of benefits to most legal immigrants and the tightening of eligibility requirements for some immigrants even after they become American citizens.

The House measure goes further in restricting welfare benefits and turns over more federal programs to the states.

"It's hard to reconcile these changes with Jewish values or American interests, and I think this will gravely harm millions of poor people," said Rabbi David Saperstein, director of the Religious Action Center of Reform Judaism.

"It will shackle the ability of Jewish social service agencies to continue their extraordinary work and it will cause enormous instability in the country," he added.

A top concern of many Jewish activists is the impact welfare overhaul will have on the hundreds of thousands of Jewish emigres from the former Soviet Union and the 30,0000 expected to immigrate this year.

If welfare reform passes in either of its current forms, Jewish activists say, the safety net for many Jewish immigrants will disappear.

"We're entirely a community of immigrants, and the idea that America is not going to extend the benefits to immigrants that it gives to others is really a deeply troubling development in America that makes a mockery of the open-handed promise on the Statue of Liberty," Saperstein said.

Critics of the reform measure say it is shortsighted because immigrants contribute about $25 billion more annually in taxes than they receive in benefits.

Although most Soviet emigres come as refugees and are considered immigrants by law, they are given special benefits because they are presumed to be fleeing a "well-founded fear of persecution."

The Senate and House bills limit refugees' benefits to five years.

With President Clinton indicating his support for a bipartisan welfare reform bill that resembles the Senate version, Jewish activists are turning to damage control.

The Council of Jewish Federations remains hopeful that Clinton can exact a compromise on the immigrant provisions in exchange for backing Congress' final action.

Jewish activists also say that dismantling safety net programs will jeopardize the well-being of poor children and their families.

In a letter to Republican congressional leaders, Phil Baum, executive director of the American Jewish Congress, urged conferees to alter the bill and "avert a serious catastrophe for the poor of the nation."

Saperstein voiced hope that Clinton could work out a compromise version, but the National Council of Jewish Women is calling on Clinton to veto the legislation outright.

"It would be a pipe dream to imagine that this bill is going to get better" in committee, said Sammie Moshenberg, of the National Council of Jewish Women.