U.S. Solicitor General Rex E. Lee yesterday urged the Supreme Court to declare that programs that provide public school teachers for classes in parochial schools do not violate the Constitution's required separation of church and state.

Lee said neither the federal government's $3 billion Title I remedial education program for disadvantaged children nor a similar state-funded program in Grand Rapids, Mich., involve the kind of "mixing" banned by the Constitution.

Taxpayers in Grand Rapids and New York City have challenged both programs, arguing that they were an unconstitutional government promotion of religion.

Federal appeals courts agreed in both cases, striking down the Michigan program that gave $3 million to religious schools in Grand Rapids in 1982 and ruling that $20 million in Title I aid to religious schools in New York in 1982 was unconstitutional.

Lee said Title I, which he called the "largest and most successful federal educational effort," was "just not the case where there is a danger" of impermissible government involvement with religion, and that there had been "no instances of mixing" taxpayer-subsidized classes with religious instruction.

Lee also urged the court to approve the more extensive Grand Rapids program, where local officials lent teachers to church schools to supplement instruction in music, art, physical education, and remedial and advanced mathematics and reading.

The court has been struggling for nearly four decades to decide what forms of public support may be provided to religious schools.

For the most part, the justices have concluded that aid such as textbooks, buses, lunches and health services was acceptable because it went directly to students.

But a proposed large-scale aid program, similar to the one in Grand Rapids, was deemed unconstitutional in 1975, and appeals courts in both cases that were argued yesterday cited that decision among others in declaring the aid unconstitutional.

Opponents of the aid programs argue that the court at least would have to overturn its 1975 ruling if it wished to approve the programs.

High court approval of the broader Grand Rapids program in particular could open the door to numerous forms of public aid to religious schools previously believed unconstitutional, opponents say.

But Kenneth Ripple, a lawyer for the Grand Rapids school board, argued that the program did not "prop up" religious schools. The taxpayer-funded classes were supplementary, he argued, not "core" or required courses, and they did not relieve the church schools of the need to teach those core courses with their own teachers.

Lawyers opposing the programs argued that both schemes call for a major and direct benefit to the religious schools and do not simply benefit the students.

University of Virginia law professor A.E. Dick Howard, arguing for Grand Rapids taxpayers who brought the case, said the distinction between what is "core" and what is only supplemental is "chimerical" -- imaginary or nonexistent.

Howard called the Grand Rapids scheme a "classic case of entanglement" between church and state, where there was a "joint exercise of authority by religious and public school" officials over the program.

"It is hard to imagine a more palpable violation of" the constitutional restrictions on mixing government and religion, Howard argued.

Lee argued, however, that if the justices struck down federal aid to the parochial schools, it would be "a real travesty" and would require parents to "give up their children's rights to a religious education in order to take advantage of the program."

The court is expected to rule in both cases by early summer.