A Turkish court said on Monday that jailed businessperson Osman Kavala must stay in prison, lengthening his detention of more than four years in a trial that has further strained Ankara's relations with Western allies.

The Council of Europe said this month its committee referred Kavala's case to the European Court of Human Rights (ECtHR) to determine whether Turkey has failed to meet its obligation to implement the court's previous judgment that he should be released immediately issued more than two years ago.

The move is the next step in "infringement proceedings," which could result in Turkey's suspension from the Council of Europe, of which it is a founding member.

President Recep Tayyip Erdoğan subsequently said when asked about the decision that Turkey will not respect the Council of Europe if it does not respect Turkish courts.

Kavala faced charges over the 2013 Gezi Park protests, a small number of demonstrations in Istanbul that later transformed into nationwide riots which left eight protesters and a police officer dead. He was acquitted of all charges in February 2020, but an appeals court overturned this verdict in January.

He was also accused of involvement in the 2016 defeated coup orchestrated by the Gülenist Terror Group (FETÖ) in Turkey and was remanded into custody on charges of spying in March.

This is only the second time the Council of Europe has used infringement proceedings against one of its 47 member states, the first occasion being a 2017 action against Azerbaijan over its refusal to release dissident Ilgar Mammadov.

In October, the embassies of the United States, Canada, France, Finland, Denmark, Germany, the Netherlands, New Zealand, Norway and Sweden called for Kavala's release in a joint statement.

Turkey's Foreign Ministry summoned the ambassadors of these countries, accusing them of meddling in the Turkish judiciary, while President Erdoğan announced he had instructed Foreign Minister Mevlüt Çavuşoğlu to declare the 10 ambassadors as persona non grata. However, the embassies took a step back, preventing the crisis from escalating further.

The diplomatic spat was resolved after the U.S. and several of the other countries issued statements saying they respected the United Nations convention requiring diplomats not to interfere in the host country's domestic affairs.

The ECtHR called for Kavala's release in late 2019 over a lack of reasonable suspicion that he had committed an offense, ruling that his detention served to silence him.

Turkey earlier this month urged the Council of Europe not to interfere in the country's independent judiciary and to be impartial toward the country in response to a decision regarding the Kavala case.