Tahir Elci, head of the bar association in Diyarbakir and a campaigner for Kurdish rights, was shot in the head on November 28, 2015 in broad daylight during armed clashes between Kurdish militants and police officers.

Minutes before his death, Elci had given a press statement calling for an end to violence in the restive southeast.

Hundreds attended a commemorative ceremony in Diyarbakir near the historic mosque where Elci was killed by a single bullet, leaving red carnations as tributes on a white sheet, an AFP photographer said.

Some held small portraits of the lawyer with the words "Baris Elcisi", a word play on his name that means "peace ambassador".

Lawyers from local bar associations, dressed in ceremonial garb, openly shed tears as they were joined by lawmakers from the main opposition Republican People's Party (CHP) and the pro-Kurdish Peoples' Democratic Party (HDP) lawmakers.

Ahmet Ozmen, who succeeded Elci as head of the bar association, told the ceremony efforts to solve the crime would continue as he criticised the "dark forces" behind the murder.

In Istanbul, dozens of lawyers paid tribute outside a courthouse with a banner vowing "we will never forget Tahir Elci", an AFP video journalist said.

- 'A political murder' -

In an interview published in opposition daily Cumhuriyet on Monday, Elci's wife Turkan criticised the progress of the investigation.

"There is no indictment, witness or suspect. So you decide how far we've come in one year," she said.

Emma Sinclair-Webb, Turkey director of Human Rights Watch, said despite an investigation not a single suspect had materialised.

She told AFP it was a "tragic irony" that the case of Elci -- who had all his career sought justice for unresolved killings -- resembled "those he struggled for all his working life".

The HDP also hit out at the lack of progress investigating what it has called a "political murder".

"For days, legal examinations of the scene were prevented, evidence was blacked out so who the perpetrator is remains unknown," it said.

Before he was killed, Elci had been detained briefly over a television interview in which he said the outlawed Kurdistan Workers' Party (PKK) "is not a terrorist organisation".

He was subsequently released before the shooting and had received death threats.

The PKK is deemed a terrorist organisation not only by Turkey but also the United States and the European Union. Over 40,000 people have been killed since the PKK began its insurgency in Turkey in 1984.

In the latest clashes with PKK rebels, two Turkish soldiers were killed on Monday in Tunceli, eastern Turkey, the official news agency Anadolu reported.

Months before Elci's death, a ceasefire between PKK militants and the Turkish state had broken down and violence returned to the southeast, but the lawyer continued to call for peace.

Elci's last words in the press statement before his death were: "We don't want clashes, guns and operations in this ancient place."