Novelists, editors, poets and journalists are becoming increasingly concerned about mass surveillance and its impact on freedom of expression in countries like Australia, the United States and Britain, a new survey has found.

It shows levels of concern among writers about official surveillance are nearly as high in democratic countries as they are in non-democratic countries that have long legacies of state surveillance.

Former NSA contractor Edward Snowden unveiled the far reach of government spy agencies. Credit:Reuters

The human rights organisation PEN International asked more than 770 writers, from 50 countries, about the ways in which government surveillance was influencing their thinking, research and writing.

The survey ran between August 28 and October 15 last year and followed a similar survey of US writers in 2013.