By Frances Harrison
BBC News, Tehran
The Iranian journalists' union has held a meeting to protest at the arrests of eight webloggers and reformist newspaper journalists in recent months.
Journalists fear political websites will be forced underground
A lawyer for three of the arrested men said he had no idea where they were being detained and what they were being charged with.
But he had been told he could meet his clients for the first time on Saturday.
The meeting began with the reading of a letter asking Iran's spiritual leader to look into the judiciary's behaviour.
It said that not only were reformist newspapers being closed down and journalists arrested, but now those working in the electronic media on internet sites were also being targeted.
Speakers said a new generation of Iranian journalists was in danger.
Most of the webloggers are in their early 20s.
One father said his son was only a computer technician, not a writer, but he had not heard from him in 40 days.
Most relatives said they had no idea which jail their sons were being held in.
A lawyer representing some of the accused said he had faced problems in getting to see his clients and obtaining authorisation to represent them.
One speaker said all journalists in Tehran should sign a power of attorney appointing a lawyer and leave it with their families in case of arrest.
Another joked it would be better to leave behind a will.
The editor of one of the political websites, Emrouz - some of whose staff have been arrested - said traditionally people used mosques, taxis and shops to discuss events, but now the internet had replaced that.
He said he feared the result of the crackdown would be that political internet sites would now go underground and become more radical and critical.