United Nations experts called on Ankara to release the head of Turkey's medical association, who was arrested after she called for an investigation into allegations of chemical weapons used by the Turkish army.
Sebnem Korur Fincanci was jailed pending trial last month on charges of "spreading terrorist group propaganda". Rights defenders said this was meant to silence her.
President Tayyip Erdogan strongly denied the accusations she made on media close to the Kurdistan Workers Party (PKK) militant group and said legal action would be taken against anyone making such allegations.
Five special rapporteurs from the U.N. Special Procedures of the Human Rights Council said on Tuesday that Turkey should stop using counter-terrorism legislation to intimidate human rights defenders and release Fincanci.
"We have documented many cases where counter-terrorism legislation and other criminal provisions have been used to harass, arrest, detain and convict civil society actors in Türkiye, including Dr. Fincanci, on spurious grounds," they said.
"Human rights defenders and medical practitioners' ability to speak truth to power must be protected. Their role in exposing human rights violations is one of the cornerstones of democratic societies," they added.
International Physicians for the Prevention of Nuclear War (IPPNW), which represents doctors and campaigns to prevent armed violence, published a report last month seeking independent investigation of possible violations of the 1997 Chemical Weapons Convention by the Turkish military.
Turkey's defence ministry and top officials also said the armed forces had never used chemical weapons in their operations against Kurdish militants.
The PKK launched an insurgency against the Turkish state in 1984 and more than 40,000 people have been killed in the conflict. It has been designated a terrorist group by Turkey, the European Union and the United States.
(Reporting by Emma Farge in Geneva; Writing by Ali Kucukgocmen; Editing by Jonathan Spicer and Ed Osmond)
