Dangerous time to be a journalist: Greste

It is now one of the most dangerous times to work as a journalist, Australian journalist Peter Greste has said in a speech written from his Egyptian prison cell.

"Rarely have so many of us been imprisoned, beaten up, intimidated or murdered in the course of our duties," he wrote in a keynote address read to London media club Frontline on Thursday night.

The beheadings of US journalists James Foley and Steven Sotloff in Syria represent a broader state of affairs faced by thousands of journalists globally, he says.

Part of the problem is the changing nature of conflict, in particular the "atrociously named" war on terror, he says.

Over the past four decades conflicts have largely involved a struggle over tangible things like territory, resources or ethnicity and have allowed the media to report from both sides with a degree of balance and neutrality.

"In these wars over stuff, the target has generally been the message rather than the messenger," he argues.

In comparison, the war on terror is indefinable, with no clear physical or ideological boundaries - "a battle between competing world views much more than a fight for land or minerals".

"And in this struggle, the message is as much a weapon as any gun," he says, pointing to Islamic State's use of social media.

Greste says there's no longer any safe turf in which to report as journalists can be accused of acting as an agent for the enemy.

"In the view of both sides, if you cross the lines in pursuit of our most fundamental principles of balance, fairness and accuracy, you effectively join the enemy," he said.

His imprisonment and the murders of Foley and Sotloff have reminded people why a free press is so important, he says.

Greste urged journalists not to take public support for granted and make a a solid commitment to the core ethical and professional standards of journalism.

He says this is also about the security of individual journalists, adding that when he is finally released it will be global support that will save him.

Greste and his Al-Jazeera colleagues Mohamed Fadel Fahmy and Baher Mohamed have been in prison since December. They were convicted in June of spreading false news and aiding the blacklisted Muslim Brotherhood group after a trial that sparked outrage and was widely condemned as farcical.

Greste and Fahmy received seven-year jail terms, while Mohamed was sentenced to 10 years. The trio have consistently denied any wrongdoing.