Turkey’s president and his supporters have been denouncing The New York Times and one of its Istanbul correspondents with growing furor for the past three days, reacting to an article and photograph about the recruitment of fighters in Turkey by the Islamic State, the militant group that has seized parts of neighboring Iraq and Syria.

Despite protests by the newspaper and press-freedom advocates, the denunciations have turned personal, punctuated by threats conveyed via email and social media against the correspondent, Ceylan Yeginsu.

On Friday, leading pro-government newspapers controlled by allies of the president, Recep Tayyip Erdogan, published front-page photographs of Ms. Yeginsu, who is Turkish, and suggested she was a traitor and a foreign agent.

Her motive, they said, was to malign Mr. Erdogan in a “perception operation” by insinuating that he is a closet supporter of the Islamic State, a group that Turkey, along with the United States and many other countries, classifies as a terrorist threat.