The nonbinding ruling followed a two-day meeting of clerics in the world's most populous Muslim nation.

Around 700 clerics, or imams, agreed to draft up guidelines on surfing the Web after receiving complaints about Facebook and other sites, including concerns they encourage illicit sex, said Nabil Haroen, a spokesman for the organizers.

They decided "Facebook is haram (or forbidden) if it is used for gossiping and spreading lies," he said, and that users also could not ask overtly intimate questions or in anyway encourage "vulgar behaviour."

But the clerics noted, too, there were many upsides to Facebook and other trendy, new forms of communication, from mobile phone text messaging to video conferencing.

It has become easier today for the young to connect, the imams' 300-word edict said, "erasing space and time constraints" and making it possible for couples to get to know - before they get married - if they really are well-suited.

Facebook had no immediate comment Friday, but said ahead of the ruling that people typically use the site to connect with their friends, family or learn about local and world issues and events.

"We have seen many people and organizations use Facebook to advance a positive agenda," said Debbie Frost, a Facebook spokeswoman.

Indonesia is a secular nation of 235 million people, 90 percent of whom are Muslim, and Facebook is the top-ranked site in the country, beating out even search engines Yahoo and Google.

Though an edict by the clerics does not carry any legal weight, it could be endorsed by the influential Ulema Council, which recently issued rulings against smoking and yoga. Some devout Muslims adhere to the council's rulings because ignoring a fatwa, or religious decree, is considered a sin.