Turkish authorities on Friday formally arrested investigative journalist Alican Uludag, charging him with insulting President Recep Tayyip Erdogan in a series of social media posts.

Uludag, who works for German broadcaster Deutsche Welle`s Turkish service, was taken from his home in Ankara late Thursday on suspicion of insulting the president and disseminating misleading information through his posts on X.

The journalist, known for his reporting on the judiciary and corruption cases, was later transferred to Istanbul, where prosecutors charged him with insulting the president - an offense that carries a maximum prison sentence of four years.

Uludag denied the allegations during questioning, insisting that his posts were legitimate criticism made in his capacity as a judiciary reporter, according to court documents published by Cumhuriyet newspaper.

His detention on Thursday drew sharp condemnation from press freedom advocates, who described it as an attack on media independence and democratic norms.

Deutsche Welle`s director?general, Barbara Massing, demanded his release, calling the arrest "a deliberate act of intimidation."

Journalists gathered outside Istanbul`s Caglayan Courthouse to protest Uludag`s detention and call for his immediate release.

The advocacy group Reporters Without Borders considers Turkey to be one of the most repressive countries for journalists, nothing that most media organizations are under government control and journalists face frequent legal pressure or intimidation.

At least 14 journalists or media workers are currently in prison, according to the Turkish Journalists Syndicate.