A Muslim cleric from Iran has claimed that social networking site Facebook is un-Islamic and being a member of it is a sin, the ISNA news agency reported last week.

Basically, going to any website which propagates immoralities and could weaken the religious belief is un-Islamic and not allowed, and membership in it is therefore a sin, the unnamed cleric said, replying to the news agency's question regarding Facebook and Iranian citizens who are members of Facebook.

Only the use of websites propagating religious criteria and not leading to any kind of ethical immoralities is of no problem, he added.

Being an Islamic nation, Iran's senior clerics have the right to pronounce opinions on matters pertaining to the society and citizens in the light of religion, which are regarded as decrees to be followed.

Facebook's official figures released last October stated that 17 million Iranians have a Facebook account, despite government restrictions on Internet.

Iranian officials have often called Internet censorship a battle against the invasion of Western culture. In 2006 and again in 2010, the activist group Reporters Without Borders labeled Iran among one of the 12 or 13 countries designated as enemies of the Internet.

Iran uses a filtering system developed by Secure Computing Corporation, SmartFilter, to block high traffic Web sites including Facebook and New York Times.

The filter also blocks access to most pornographic sites, gay and lesbian sites, activist sites, news media, sites that provide tools to help users cloak their Internet identity and other sites defined as immoral on various grounds by the government.