A court has convicted a former Miss Turkey of insulting President Recep Tayyip Erdogan through social media postings and handed her a 14-month suspended sentence.

The court in Istanbul found 27-year-old model Merve Buyuksarac guilty of insulting a public official but immediately suspended the sentence on condition that she does not re-offend 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.

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

Since becoming president in 2014, Mr Erdogan has filed close to 2,000 defamation cases under a previously seldom-used law that bars insulting the president. Free speech advocates say the law is being used aggressively to silence and intimidate critics.

The trials have targeted journalists, academics and even schoolchildren. Coupled with a crackdown on opposition media and journalists, the trials have sounded alarms over the erosion of rights and freedoms in a country that was once seen as a model of Muslim democracy.

Mr Erdogan caused an uproar last month when, on the basis of an archaic German law that criminalises insulting foreign heads of state, he went after a German comedian who mocked him in a profanity-packed poem.

Mr Erdogan rejects accusations of growing authoritarianism. He also denies curbs on freedom of expression, citing what he says are large numbers of offensive articles against him and his family as proof.

"These insult trials are being initiated in series, they are being filed automatically," Mr Telci said after the verdict. "Merve was prosecuted for sharing a posting that did not belong to her. My client has been convicted for words that do not belong to her."

Thousands of others also posted the poem, which is a satirical adaptation of the Turkish national anthem. It did not mention Mr Erdogan by name, but alluded to a corruption scandal that allegedly involved his family.

Before the verdict was announced, Mr Erdogan's lawyer, Hatice Ozay, argued in court that Buyuksarac's Instagram post cannot be considered a criticism, but rather an attack on Mr Erdogan.

"This constitutes an attack on personal rights and for this reason we ask that the defendant be punished," the state-run Anadolu Agency quoted her as telling the court.

Also on Tuesday, veteran journalist Cengiz Candar appeared in court in Istanbul accused of insulting Mr Erdogan in a series of columns he wrote last summer criticising Turkey's renewed conflict against Kurdish rebels.

Candar, a former columnist for Radikal and Hurriyet newspapers, faces up to four years in prison if found guilty.

Candar rejected the charge. He said that, in 40 years as a journalist, he had covered and known seven presidents.

"I was an advisor to the late (President) Turgut Ozal, I had a friendship with the previous president, Abdullah Gul," Candar said. "I know how to address and act before a president. There can be no accusation of insulting a president where I am concerned."

Outside the courthouse, Candar told reporters: "These court cases must come to an end. Secondly, these trials must immediately end with acquittals so that the presidency of the Turkish Republic can preserve its respectability."

His case was adjourned until September.