ASAN, South Korea — Brides in white gowns and Japanese kimonos joined grooms in black suits and red ties today for the Unification Church's biggest mass wedding in a decade — a spectacle church officials say involves 40,000 people around the world.

The "blessing ceremony" is the church's largest since 1999, and may well be the last on such a grand scale officiated by the 89-year-old Rev. Sun Myung Moon, the controversial founder of the Unification Church.

Nearly a half-century after arranging the marriages of 24 couples in his first mass wedding, Moon offered blessings today for more than 20,000 people gathered at Sun Moon University, the school he founded in Asan, south of Seoul.

About half are marrying for the first time, some in marriages arranged by Moon himself; the rest are renewing their wedding vows. Twenty-thousand others are expected to watch via Internet broadcast at simultaneous ceremonies taking place from Sweden to Brazil.

The mass wedding comes as Moon is moving to hand day-to-day leadership over to his children. The Rev. Moon Hyung-jin, the 30-year-old son tapped to take over religious leadership, opened the ceremony at the flower-festooned altar.