A suicide bombing has left at least five people dead in a busy shopping area popular with tourists and locals in Istanbul.
The governor of Istanbul Province, Vasip Sahin, initially said four people had been killed, including the bomber, but the death toll rose under an hour later as another victim died of their injuries in hospital.
Health officials said 36 people were injured in the attack in İstiklal Avenue, also known as Istiklal Street, including 12 foreign nationals.
Several Israelis were among the wounded, the country’s foreign ministry said, and German, Iranian, Icelandic and Emirati citizens were also hurt.
Ireland's minister of trade and foreign affairs, Charlie Flanagan, confirmed "a number" of Irish citizens were among the injured.
CCTV footage of the explosion showed shoppers milling around on the street when the bomb was detonated next to a group of people standing on the pavement.
People could be seen lying motionless on the floor as survivors ran for cover. Two children were among those injured, the Dogan news agency reported.
The wide pedestrianised avenue is one of the most famous streets in Istanbul, lined with boutiques, art galleries, theatres, cafes and foreign consulates, leading to Galatasaray Square.
Local residents said the area hits its peak on weekends afternoon and evenings and that 11am local time (9am GMT), when the blast hit, would have been comparatively quiet.
Growing speculation that the blast was another terror attack aimed at hitting Turkey's tourist industry and liberal social scene could not be confirmed and there was no immediate claim of responsibility.
Turkish officials told Reuters evidence suggested the attacker was from either the banned Kurdistan Workers Party (PKK) or Isis, and may have been aiming for a more crowded area.
“The attacker detonated the bomb before reaching the targeted point because they were scared of the police,” one official said.
In pictures: Istanbul suicide bombing
In pictures: Istanbul suicide bombing
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Medics try to help wounded people after an explosion in Istiklal Street in Istanbul, Turkey, 19 March 2016.
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People jump a police line to flee the scene of an explosion on the pedestrian Istiklal avenue in Istanbul on March 19, 2016.
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People take shelter inside a shop after an explosion on the pedestrian Istiklal avenue in Istanbul on March 19, 2016.
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A girl cries in front of injured people on the scene of an explosion on the pedestrian Istiklal avenue in Istanbul on March 19, 2016.
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People flee the scene of an explosion on the pedestrian Istiklal avenue in Istanbul on March 19, 2016.
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Turkish police push people away after an explosion on the pedestrian Istiklal avenue in Istanbul on March 19, 2016.
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Police inspect the site after an explosion in Istiklal Street in Istanbul, Turkey, 19 March 2016.
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Turkish policemen stand in a cordon off street after a suicide bomb attack at Istiklal Street in Istanbul, Turkey, 19 March 2016.
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Emergency services inspect the area following a suicide bombing in a major shopping and tourist district in the central part of the city on March 19, 2016 in Istanbul, Turkey.
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Police secure the area following a suicide bombing in a major shopping and tourist district in the central part of the city on March 19, 2016 in Istanbul, Turkey
Turkish authorities imposed a temporary broadcast ban governing coverage of the attack on Saturday, while Facebook and Twitter were also blocked. The measures are frequently imposed after terrorist attacks in the country.
A spokesperson for the Foreign and Commonwealth Office said officials were monitoring the situation but could not yet confirm whether any British nationals were injured.
It had previously warned of a a high threat from terrorism in Turkey, saying that attacks from a range of Islamist and Kurdish groups could be indiscriminate and target areas frequented by foreigners.
The lead singer of British band Skunk Anasie, Skin, said she was in a hotel overlooking the street at the time of the blast and described the building "shaking like paper".
There has not yet been any update to the UK Government's travel advice for the country but Germany issued a bulletin advising citizens to stay inside their hotels.
Saturday's explosion came after a bombing claimed by a Kurdish militant group killed 37 people in Ankara on Sunday and a suspected Isis suicide bomber killed 13 tourists at Istanbul's Sultanahmet Square in January.
Both factions have committed atrocities in Turkey at an increasing rate over the past year as Turkey continues military operations in Kurdish areas in the south-east and the Syrian war rages over the border.
Germany closed its embassy in Ankara and a consulate and German school in Istanbul last week because of a warning over an imminent attack.
Both the Istanbul school and consulate are situated near Istiklal Street but it was unclear if the threat was linked to Saturday's attack.
Philip Hammond, the Foreign Secretary, condemned the "senseless bombing" on Twitter, while France's foreign minister, Jean-Marc Ayrault, called it a “despicable and cowardly act” and the American embassy in Turkey said it was in mourning.
Turkey has been heightening security in the city and Ankara in the run-up to a Kurdish spring festival of Newroz on 21 March, which Kurds in Turkey traditionally use to assert their ethnic identity and demand greater rights.
The Turkey's Peoples' Democratic Party (HDP), a Kurdish-rooted opposition party, condemned the bombing.
“Just as in the Ankara attack, this is a terrorist act that directly targets civilians,” a spokesperson said. “Whoever carried out this attack, it is unacceptable and inexcusable.”
Additional reporting by agencies