At least five people have been killed and 36 injured in what is believed to be a suicide bomb attack in central Istanbul, government officials have said.
The explosion on Saturday morning occurred on Istiklal Avenue, a busy pedestrian thoroughfare lined with shops and boutiques near Taksim square in the historic Beyoglu district of the city.
The bomber, who was reportedly wearing a suicide vest, is said to be among those killed.
Seven of the 36 wounded were seriously injured, officials said, while 12 of the injured were foreign.
The Israeli foreign ministry has said several of its citizens were hurt in the attack, while German, Iranian, Icelandic, Emirati and Irish citizens were also among the injured.
There has not yet been a claim of responsibility for the attack, although Turkish official told Reuters evidence suggested the attacker was either from Isis or the banned Kurdistan Workers Party (PKK).
The latest explosion in Istanbul comes after two recent suicide bomb attacks on the Turkish capital city Ankara.
The militant Kurdish Freedom Faclons (Tak) group claimed responsibility for the car bomb attack that killed 37 people and injured at least 125 more in Ankara, the Turkish capital, on 13 March.
On 12 January, 13 tourists were killed and 14 were injured in a suicide attack close to the Blue Mosque, another tourist hotspot, in Istanbul's historic Sulthanahmet Square.