Leading journalism, publishing and freedom of expression groups have joined forces to lobby the Iranian government to release journalists imprisoned in the country.

The Our Society Will Be a Free Society campaign is backed by Index on Censorship (IOC), the Committee to Protect Journalists (CPJ) PEN, Reporters Without Borders (RSF), Canadian Journalists for Free Expression and the International Publishers Association (IPA).

Its launch, which will coincide with the start of Iranian New Year on 20 March, comes a week after new figures from the CPJ suggested that more journalists were currently imprisoned in Iran than have been held by any other country since 1996.

According to the CPJ figures, Iranian authorities are now holding at least 47 journalists in prison with at least 26 journalists jailed in the last two months alone.

The number of imprisoned journalists in Iran has more than doubled since 1 December 2009, when the CPJ's annual worldwide census of imprisoned journalists found 23 journalists were in prison in the country. This increase in imprisonments means Iran currently has more journalists imprisoned than any other country, including China which had the most (24) according to the 1 December survey.

While many of those currently held where imprisoned following the post-election violence in June last year, the new figures from the CPJ suggest that Iranian authorities are still targeting independent and opposition journalists.

The campaign, which will urge Iranian authorities to release imprisoned writers and bloggers as well as journalists, will call on international governments to place pressure on Iran. Events will be organised in Europe and North America throughout Spring to raise support, the campaign said.

An open letter from the campaign organisers has been sent to Iran's Ayatollah Ali Khamenei, while Maziar Bahari, the Iranian-Canadian reporter for Newsweek who was imprisoned in Tehran from June to October 2009 has penned an op-ed for the International Herald Tribune showing his support for the campaign.

"We must send these courageous men and women, and the nearly 50 journalists currently behind bars, a clear message of support. Iran is now the biggest jailer of journalists in the world. President Ahmadinejad should be ashamed of this fact and release our colleagues immediately," says Paul Steiger, chairman of the CPJ, in a release.

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