ANKARA, Turkey — A court on Tuesday convicted a former Miss Turkey of insulting President Recep Tayyip Erdogan through social media postings and gave her a 14-month suspended sentence, amid deepening concerns that the country is moving toward an increasingly authoritarian form of rule.

The court in Istanbul found Merve Buyuksarac, 27, guilty of insulting a public official, but immediately suspended the sentence on the condition that she does not reoffend within the next five years.

Her lawyer, Emre Telci, said he would file a formal objection to the verdict and appeal her case at the European Court of Justice in Strasbourg, France.

Ms. Buyuksarac, a model, who was crowned Miss Turkey in 2006, was briefly detained last year for sharing a satirical poem on her Instagram account in 2014. Prosecutors considered it insulting to Mr. Erdogan, who was prime minister at the time. She has denied insulting him.