Think of this next time someone says that George Bush has "destroyed civil liberties" in this country:

"While the outcome of the recent arrests in connection with SMS messaging is not clear yet, what is certain is that SMS jokes have already put some people into serious trouble," wrote the website Rooz Online.

The clampdown is in line with the authorities' uncompromising stance on the internet and bloggers. Wary of modern communications as a means of spreading political dissent, Iran is second only to China in the number of websites it filters - using technology made in America.

Large numbers of the nation's estimated 70,000 to 100,000 bloggers have faced harassment or imprisonment. The regime has acknowledged monitoring text message traffic. It first admitted it had access to text traffic last December when a military plane carrying more than 100 journalists crashed shortly after take-off at Tehran airport.