President Reagan is expected to announce rule changes today to strengthen restrictions on abortion in the federal government's family-planning program, administration and congressional sources said yesterday.

Reagan's expected announcement at a meeting with antiabortion groups would be the latest step in a long and bitter struggle over the program. The changes would not go as far as some antiabortion groups want, but a White House source said, "It is significant that with the lineup we've got now, we've been able to get these changes through after six years of stalemate."

Some of these changes were pushed earlier by antiabortion groups, but the Department of Health and Human Services had declined to make them on grounds that the law had to be changed first. Sources said that Reagan nevertheless has decided to go ahead with them. The action occurs as the Senate Labor Committee, headed by Sen. Edward M. Kennedy (D-Mass.), is scheduled to open hearings today on the program. In the past, Kennedy and such groups as Planned Parenthood and the National Family Planning and Reproductive Health Association have opposed these kind of changes.

The law already forbids the use of any family-planning program funds to perform or advocate abortion.

But a guideline in the rules requires a federally funded family-planning clinic to tell a woman, if she comes in for information on how to handle an unexpected pregnancy, that one of her options is an abortion. It must do this in a neutral way and must refer her to a nonfederally funded abortion facility if she then requests a referral.

The president is expected to announce that in the future a federally funded family-planning clinic does not have to give a woman information about options and therefore doesn't have to provide any followup referral.

A second major change would bar a federally funded family-planning clinic from operating at the same site as an abortion facility that is operated with nonfederal funds. Under the law, an organization that uses its own nonfederal funds for abortion may qualify for federal grants to run family-planning clinics as long as it does not use the federal money to perform abortions. In some cases, organizations use the same or adjoining suites of offices for both purposes.

A third rule to be announced by the president would bar any federal family-planning funds from use in activities or programs that encourage, promote or advocate abortion, a restatement but in much stronger language of the ban on the use of federal program funds to perform or advocate abortion.