Istanbul police detained 20 suspected members of an ultra-left militant group on Tuesday.
Police teams raided 24 locations in nine districts of the city with support units and helicopters, said unnamed police source speaking on condition of anonymity due to restrictions on speaking with the press.
They detained some 20 suspected members of the Marxist-Leninist Communist Party (MLKP).
Suspects were accused of participating in unauthorized rallies, attacking police, and training recruits in bomb-making in Syria and facilitating their return to Turkey.
The MLKP was founded in 1994 and in 2007 was added to a list of active "terror" organizations in Turkey.
In July 2015, the organization attempted to bomb the headquarters of Star Media Group in Istanbul.
Bomb disposal experts destroyed the device in a controlled explosion.
