WASHINGTON — Federal officials have moved closer to overturning a decades-old ban on blood donations from gay and bisexual men, but activists said the proposed alternative would continue to stigmatize men who have sex with men.

The Food and Drug Administration said Tuesday it will recommend lifting the lifetime ban early next year, replacing it with a policy barring donations from men who have had sex with another man in the previous 12 months. The change would overturn a 31-year-old policy that many medical groups and gay activists said is no longer justified, given advances in HIV testing.

But activists questioned whether requiring a year of celibacy from gay men amounted to a significant policy shift.

“Some may believe this is a step forward, but in reality, requiring celibacy for a year is a de facto lifetime ban,” Gay Men’s Health Crisis, a New York-based nonprofit that supports AIDS prevention and care, said after the announcement.

The blanket ban dates from the early years of the AIDS crisis and was intended to protect the blood supply from what was a then little-understood disease. But many medical groups, including the American Medical Association, said the policy is no longer supported by science.