Indonesia's Ulema Council of religious authorities renewed a fatwa forbidding Muslims - including the president - from attending Christmas celebrations and offering holiday wishes to Christians, reports say.
President Susilo Bambang Yudhoyono and Vice President Boediono are scheduled to attend a national Christmas celebration on December 27.
"Even though they are the country's leaders, they are forbidden to attend such Christmas celebrations," Maman Abdurrahman, chairman of Muslim organisation Persis, was quoted as saying by The Jakarta Post.
But leaders of Nahdlatul Ulama and Muhammadiyah, two of the country's largest Muslim organisations, have said wishing people a happy Christmas is not forbidden and is a form of religious tolerance.
Indonesia is a secular country with the largest Muslim population in the world.