(Reuters) - A Turkish prosecutor is seeking prison terms for two journalists who republished the cover of the French satirical magazine Charlie Hebdo featuring an image of the Prophet Mohammed, their newspaper said on Wednesday.

Ceyda Karan and Hikmet Cetinkaya, columnists at Cumhuriyet daily, both face jail terms of 4-1/2 years for allegedly "insulting people's religious values" for reprinting the caricature of Islam's prophet following the Jan. 7 attacks on Charlie Hebdo in Paris that killed 12 people, Cumhuriyet said on its website, citing a copy of the indictment.

The secular Cumhuriyet faced security threats when it became one of five international publications that printed excerpts of the edition of Charlie Hebdo that appeared after the attacks to show its solidarity with the cartoonists.

"We are being threatened with prison for defending free speech," Karan told Reuters. "To threaten a journalist because he or she printed a drawing that does not include an insult can only come from a religious, authoritarian government.

"Neither of us will abandon our defence of free speech," she said, adding she has had bodyguard protection since January.

The prosecutor opened his investigation into Cumhuriyet after Turkish Prime Minister Ahmet Davutoglu accused the paper of "incitement" for publishing the Charlie Hebdo excerpts.

Davutoglu marched with world leaders in Paris after the attacks in what he said was an expression of his opposition to terrorism and warned Islamophobia could fan Muslim unrest.

Muslim Turkey's constitution strictly separates state and religion but its penal code makes it a crime to insult religion.

Turkey frequently faces criticism from rights groups and Western governments for curbing press freedom, including jailing journalists for their reporting. Earlier on Wednesday, a prosecutor sought to drop charges against a Dutch reporter for her reporting on the Kurdish conflict.