Turkey has said the suicide bomber who killed 10 German tourists in an explosion in Istanbul on Tuesday entered the country as a refugee and had not been monitored because he was not on any watch lists.

Speaking a day after the attack, which Ankara has blamed on Islamic State, the Turkish prime minister, Ahmet Davutoğlu, said four more people had been detained, bringing the number of suspects to five.

The attack, which also left 15 people wounded, took place in the Sultanahmet district in the heart of city’s historic centre. It was the latest in a spate of violent incidents in a country struggling to contain the fallout from the Syrian war as well as a Kurdish separatist insurgency.

In comments published in the Turkish media on Wednesday, a tour guide who had been accompanying the group of German tourists said the bomber “was a young bearded man who looked like a Turk”.

“He had a innocent face and was wearing modern clothes,” Sibel Şatiroğlu was quoted as telling the daily Hürriyet newspaper.

In a harrowing account, Şatiroğlu said she saw the man preparing to launch the attack after blending into a group of 33 German citizens visiting the Theodosius obelisk.

“I heard a click sound while I was telling the group about the obelisk. I thought it was strange and looked around,” she said.

“I saw the young man pull the pin and I shouted ‘Run!’ in German. Then we started to run away, and the bomb instantly exploded.”

Eleven people were still being treated for injuries sustained in the blast, including nine Germans, a Norwegian and a Peruvian national, officials said.

Earlier on Wednesday, the Turkish interior minister, Efkan Ala, said at a press conference with his German counterpart that Turkey was “seriously investigating” the attack and its perpetrators, and that the first suspect had been detained after the blast on Tuesday.



Three Russian citizens were also detained on suspicion of links to Isis, the foreign ministry in Moscow confirmed. Interfax news agency quoted Russian officials as saying they were trying to get access to the detainees, one of whom was on an international wanted list, but that they had no known connections to terrorism. The three were among dozens arrested across Turkey following the attack.



Davutoğlu said on Wednesday that Russia’s entry into the Syrian civil war had become a barrier to Turkish air strikes against Isis, and that the Russian air force appeared to be protecting the radical Sunni militants.

Asked whether Turkey planned air strikes against Isis in response to the bombing in Istanbul, he said the country would act at a time and in a manner that it saw fit.