Communications Minister Tifatul Sembiring, a member of the conservative Islamic party, called a news conference on the eve of the month-long period of dusk-to-dawn fasting at which he renewed a promise to act against porn sites.

Quoting a poem, Mr Sembiring called on Muslims to "keep hearts clean in the holy month" and said that he would target websites and media that carried sexual content.

Already 200 internet service providers in Indonesia have since last month agreed to block sites that displayed sexual activity and nudity, and "their efforts are extraordinary", Mr Sembiring said.

"It's not an easy task as there are four million local and international porn sites," he said, but added that he was unable to say how many sites had been shut out of Indonesia.

"I've promised before there will be efforts to close porn sites... This Ramadan hopefully traffic to porn sites can be reduced by more than 90 per cent," he said.

Mr Sembiring's call follows President Susilo Bambang Yudhoyono's support for a web filter, saying in June that his country must not "stay naked and be crushed by the information technology frenzy".

With 240 million people making it the world's most populous Muslim-majority country, Indonesia was scandalised in June by the online release of videos apparently showing local celebrities having sex.

Freelance magazine photographer Ahmad Fadilah, 35, who admitted to watching internet porn occasionally, said he hoped access would only be restricted to hardcore porn sites such as those showing bestiality and unnatural sex.

"Go ahead and block the really vulgar and disgusting ones but please leave the beautiful, artistic ones alone," Mr Fadilah said.

"Anyway, if sites are blocked, there are other ways to access porn, like from VCD.

"Sometimes people like to say Ramadan is a month to cleanse your heart and mind. But people still watch porn and who will find out if they do it quietly?"