Syrian musician Omar Souleyman has been arrested in Turkey on terrorism charges, the Guardian reports. He is being detained and questioned by Turkish authorities about alleged associations with the Kurdistan Workers’ Party (PKK), a Kurdish militant separatist political organization and armed guerrilla movement operating in Turkey.

Souleyman’s son denies the terrorism charges, saying that his father has no political affiliations and that a “malicious report” was filed against him. According to his manager, he is being questioned over reports that he had recently travelled back to an area of Syria controlled by the People’s Defense Units (YPG), the PKK’s Syrian affiliate.

Souleyman is an internationally known singer and musician who has worked with Björk, Four Tet, Damon Albarn, and Diplo and performed at the 2013 Nobel peace prize ceremony. He has been living in Turkey since the start of the Syrian civil war in 2011, opening a free bakery in the border town of Akçakale to serve needy Turkish families and Syrian refugees.