Updated

Istanbul's police chief says an Islamic State militant who stabbed a police officer to death while in custody was an "internationally wanted terrorist."

Mustafa Caliskan said Monday the man — who was shot and killed by other officers after the attack — was planning a major assault, which his detention allegedly thwarted. Caliskan was speaking at a memorial for the 24-year-old slain officer.

The suspected IS suicide bomber was detained in an anti-terror operation and was being taken to Istanbul's main police station when he fatally stabbed the officer late on Sunday.

It was unclear how the suspect had access to a knife. There was no word on his identity or nationality.

Turkey has endured multiple bomb attacks since 2015, blamed on IS or Kurdish militants.