Turkey's state-run news agency says a court has sentenced three people to life prison terms for their involvement in an Islamic State group suicide bombing in 2016 at Istanbul's historic Sultanahmet district that killed 12 German tourists.

Anadolu Agency says the court in Istanbul delivered its verdict on Wednesday.

Turkish authorities said the suicide bomber, a Syrian identified as Nabil Fadli, was affiliated with IS. He set off the bomb near a group of German tourists steps away from the landmark Blue Mosque.

The attack, which was one of several to rock Turkey since 2015, also wounded 15 people, including nine Germans and citizens of Norway, Peru and South Korea.