Can Dundar, editor in chief of Turkey's leading opposition daily, Cumhuriyet, has been fined some $10,000 for allegedly insulting President Recep Tayyip Erdogan, the journalist and his lawyer say.
Dundar's lawyer, Blent Utku, was quoted by the dpa news agency on April 25 as saying the case against the journalist was related to articles he wrote about a corruption scandal that rocked the Turkish government in 2013.
The exact reason behind the Istanbul court's April 25 ruling has not yet been made public. The lawyer said he will appeal the ruling.
Dundar said on his Twitter account that "If revealing the truth is a crime, we will keep on committing it."
Dundar is also standing separate trial for allegedly seeking to overthrow the government, a charge that stems from his reporting on weapons shipments from Turkey to Syrian rebel groups.
Dundar and co-defendant Erdem Gul, the newspaper's Ankara bureau chief, face life in prison if convicted.
Nearly 2,000 people are facing prosecution in Turkey for insulting Erdogan, whom critics accuse of using the courts to stifle dissent.
On April 24 a Dutch journalist of Turkish descent was arrested a week after criticizing Erdogan in an article.
In Germany, the authorities have accepted a request from Turkey to open a criminal probe against a comedian who read out on TV a satirical poem about Erdogan.
Turkey demanded the comedian be prosecuted for insulting a foreign head of state.