Hundreds of Iranian online journals have been protesting against media censorship by renaming their websites after pro-reformist newspapers and websites that have been banned or shut down by the authorities.
The reformist Emrooz website was blocked - but has now re-appeared
Many of the websites, known as blogs or weblogs, have also posted news items from the banned publications on their websites.
The protest was started by blogger Hossein Derakhshan, a student at Toronto university in Canada.
He told the BBC that although he felt the action was symbolic, he wanted to show Iranian authorities "that they would not be able to censor the internet in the same way as they have managed to control other media".
He said he was delighted with the response.
The hardline Iranian press has published a personal attack on him, he said, "which is proof that the authorities must be worried by the bloggers' protest".
Earlier this month, three reformist websites - Emrooz, Rooydad and Baamdad - re-appeared in a stripped-down form after having been blocked by the authorities.
One of them moved the content of its site onto a blog as a means of getting around the block.
It is thought that the number of Iranians keeping blogs is now between 10,000 and 15,000.
However, some recent reports have now suggested that Iranian authorities are considering the creation of a national intranet - an internet service just for Iran - which would be separate from the world wide web.
This would potentially mean that users would not be able to access anything the authorities do not want them to see.
But Mr Derakhshan said he and his fellow bloggers are working on a strategy to get around the intranet, using email subscription services.