An explosion near a ferry terminal on the outskirts of Istanbul has injured at least four people, one of them a policeman, according to Turkish news agencies.
Reports said that none of the four was seriously injured in the explosion on Sunday.
"It was a bomb detonated with the intent to do damage," the Reuters news agency reported an unnamed police officer as saying.
No further information was immediately available.
Last week, two bombs exploded in the Aegean coastal city of Izmir, killing one and wounding several others.
Bombs are not infrequent in Turkey, where the authorities have blamed several groups, including Kurdish separatists, for attacks against civilians.