Turkish authorities on Tuesday detained prominent philanthropist Osman Kavala over charges linked to a failed 2016 coup attempt, hours after he was acquitted on terrorism-related charges.
Istanbul prosecutors said they would appeal the court's ruling which acquitted Kavala, 63, and eight other activists of organising the 2013 Gezi park protest in an attempt to overthrow the Turkish government.
His renewed detention, they added, relates to a separate investigation into his role in the July 15, 2016 attempted coup.
The government of President Recep Tayyip Erdogan blames the US-based Muslim cleric Fethullah Gulen of being behind the failed coup and have sicne then cracked down on his alleged followers, arresting tens of thousands under a state of emergency.
Kavala's fresh arrest and the charges he now faces have been described as "vindictive and lawless" by Philippe Dam, Human Rights Watch's advocacy director for Europe and Central Asia.
The NGO's director for Turkey, Emma Sinclair-Webb, said that "the bogus charges should be dropped in this show trial".
For the Europan Parliament's rapporteur on Turkey, Nacho Sanchez Amor, the move by the Turkish authorities shows the country's judiciary is "back again in the dark period" while the Council of Europe (CoE), an international organisation promoting human rights and democracy, said it amounted to "ill-treatment".
"The re-arrest of Osman Kavala after his acquittal in the Gezi trial yesterday, under separate charges concerning the coup attempt on 15 July 2016, is a perfect illustration of the acute problems of the Turkish judiciary," Dunja Mijatovic, the CoE's commissioner for human rights said in a statement.
"I call on the Turkish judiciary and the Council of Judges and Prosecutors to assume their responsibility, by not giving a judicial confirmation to such abuses of criminal proceedings, and by reining in such prosecutors," she went on.
Kavala was arrested in November 2017 over his suspected role in the Gezi park protest.
The 2013 movement had started as a demonstration against the planned development of a shopping mall on the site of a small park in central Istanbul but quickly morphed into a wide protest nationwide, drawing 3.6 million protesters.
Prosecutors accused Kavala and several others of organising and financing the protest to overthrow the government — which they have always denied — and sought a life sentence in solitary confinement.
But the panel of judges said the authorities had failed to produce enough "concrete and certain evidence" and acquitted the nine activists.
The more than 300 people who had attended the trial broke out in applause when the ruling was read.