Earlier on Sunday, Turkey's justice ministry said Turkey had started efforts to have Muslim extradited to Ankara.
The Turkish Justice Ministry said he was being tried in absentia for his alleged involvement in a March 2016 auto bomb attack on Turkey's capital, which killed 36 people and injured 125.
Czech police say that have arrested and placed in detention a 67-year-old foreigner at the request of Turkey's Interpol.
He was reported to have been in the Czech capital to attend a biannual conference on the Middle East which was discussing the war in Syria, the Turkish government and the Israeli-Arab conflict.
Turkish security officials and the Ministry of Justice have begun the administrative process for the extradition of Salih Muslim.
PKK, listed as a terrorist group by the United States and the European Union, has waged a bloody insurgency in Turkey since 1984.
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Muslim was replaced as co-chair of the PYD previous year, but remains a member of the diplomatic committee of the TEV-DEM political coalition that issued the statement on his arrest.
The PYD, which Turkey considers a "terrorist group", is the main political Kurdish force in the north of Syria. He was replaced in 2017.
On Sunday, Turkey's Deputy Prime Minister Bekir Bozdag told Turkey's Anadolu Agency that military operations in the Afrin region would not be affected by the UN Security Council Resolution seeking a ceasefire in Syria.
PKK resumed armed attacks in July 2015 and the Turkish authorities accused the PYD and YPG of providing PKK with fighters, arms and equipment.
The operation is being carried out under the framework of Turkey's rights based on worldwide law, UN Security Council's decisions, self-defense rights under the UN charter and respect for Syria's territorial integrity. Turkey has recently launched a military operation called "olive branch" in the Syrian region of Afrin, which is aimed against Kurdish militias, including the PYD.