Iran monitored eight million Facebook accounts with new software and will watch other social media sites for content that contravenes the Islamic Republic's moral codes, state television reported on Monday.

The Centre for Investigation of Organised Crime, a branch of the elite Revolutionary Guards Corps (IRGC), accused Facebook of spreading immoral content and said it had arrested several users.

“...  is trying to push its users towards immoral content via its suggestion system, by making them choose harmful, decadent and obscene content over beneficial and educational subject matter," the IRGC said in a statement cited by state TV and other Iranian media.

Iran blocks access to social media sites Facebook, Twitter and YouTube but millions of Iranians easily get around that by using virtual private networks (VPNs).

However, that does not make Iranians immune from state surveillance and last year three men and three women who posted a video of themselves singing and dancing along with a Western pop song were arrested.

As well as testing the boundaries of Iran's Islamic dress and morality code, social networking sites were used to help organise massive anti-government protests in 2009 that Tehran said were stirred up by foreign powers.

The cyber security directorate will expand its "Spider" programme to monitor other social media including Instagram, Viber and WhatsApp, the IRGC said.

In December, Communications Minister Mahmoud Vaezi introduced a policy of "smart filtering" to improve the efficacy of its censorship, and said the policy would be fully in place by June. – Reuters