Turkish authorities are questioning six suspects detained during simultaneous anti-terrorism police raids in four cities, according to the state-run agency.

The Anadolu Agency reported Friday that authorities released six other people without charge who were detained during the raids in Adana, Hatay, Mersin and Istanbul.

Authorities have refused to identify the suspects, but the private Dogan news agency said all 12 were detained during a police sweep on suspected members of al-Qaida or of Jabhat al-Nusra, the al-Qaida linked opposition force fighting in Syria.

Huseyin Avni Cos, governor of Adana province, said some chemical materials were confiscated during the raid, but denied a report which claimed that sarin gas was seized during the raids. He said experts were trying to determine what the materials could be used for.