The United Nations on Monday called on Ankara to investigate the suspected shooting of a group of unarmed people in Turkey's southeastern Kurdish-dominated region, caught in "extremely shocking" video footage.
Speaking to reporters in Geneva, UN rights chief Zeid Ra'ad al-Hussein voiced outrage at an incident caught on camera in the town of Cizre around 10 days ago.
The footage, apparently shot by a cameraman named Refik Tekin, shows a group of unarmed civilians, led by a man and woman holding white flags, pushing what appears to be dead bodies on a handcart, as they are observed at a distance by security forces in an armoured military vehicle.
Suddenly, "they are apparently cut down in a hail of gunfire," Zeid said, describing the footage as "extremely shocking."
The video, which can be viewed on Youtube, shows a chaotic scene in which Tekin falls to the ground, his own blood apparently spilling in front of the lens, with what looks like dead bodies splayed on the ground in front of him.
"I'm very concerned that the cameraman, who was himself wounded, is facing arrest once he leaves hospital," Zeid said.
"Filming an atrocity is not a crime, but shooting unarmed civilians most certainly is," he added.
"It is essential there is a thorough, independent, impartial investigation into this and any other events that have led to the wounding or killing of civilians."
Vowing to flush out the outlawed Kurdistan Workers' Party (PKK) from Turkey's urban centres, the authorities have in recent weeks enforced curfews in three locations in the southeast to back up military operations that activists say have killed dozens of civilians.
Cizre in Turkey's Sirnal province near the Iraqi border has been under curfew since December, when the army launched an "anti-terror operation", marking a new escalation in six months of fighting with the PKK since a two-and-a-half-year truce collapsed.
The army said last week a total of 20 Kurdish rebels were killed in Cizre and nearby Sur, bringing the total number of militants killed in the two towns since December to some 600.
Zeid on Monday warned that the video showing the apparent shooting of unarmed civilians "raises major question marks about what exactly has been going on in Cizre and other parts of southeastern Turkey, which the security forces have allegedly sealed off from the outside world."
"I am urging the Turkish authorities to respect the fundamental rights of civilians in its security operations," he said.
He acknowledged Ankara's duty to protect the Turkish population from violence, saying he had been informed by the government that 205 members of the Turkish police, gendarmerie and military had been killed between July 20 and December 28 last year.
But he urged Turkish authorities to do more to protect human rights during military or security operations, insisting that "if state operatives commit human rights violations, they must be prosecuted."
Zeid also said that the treatment of Tekin only added to his "already considerable concern" about the treatment of journalists in Turkey.
"The country has an alarming number of journalists and other media operatives either already convicted or awaiting trial," he said.
He said the easiest way for Turkey to show it respects human rights and international law would be "to free all those... who have been detained or prosecuted simply for recording or criticising the actions of the state."