Eleven held in Istanbul over tourists' deaths from suspected poisoning

• Four members of a Turkish-German family died from suspected poisoning in Istanbul while on holiday, including a father, mother, and their two young children.
• Eleven people have been detained, including food sellers and hotel and pest control staff, as investigators pivot from food poisoning to the possibility of lethal pesticide exposure at their hotel.

Eleven people have been detained in connection with the deaths of four members of the same family from suspected poisoning in Istanbul, the state-run Anadolu news agency said Monday.

A Turkish-German woman, her husband and their two children, who were on holiday from Germany in Turkey's largest city, fell ill on Wednesday after eating several popular street food dishes in the waterside neighbourhood of Ortakoy, at the foot of a bridge spanning the Bosphorus.

They were taken to hospital but the two children died on Thursday and the mother a day later. Anadolu identified them as Cigdem Bocek, her son Kadir, six, and her daughter Masal, three.

The father, Servet Bocek, died Monday after several days in intensive care.

Istanbul prosecutors opened an investigation, initially focusing on suspected food poisoning.

But evidence has since emerged that the family may have been exposed to pesticides in the hotel where they were staying, Turkish media reported.

Quoting investigators, Turkey's Hurriyet newspaper said a substance was sprayed in a room on the ground floor of the hotel to combat a bed bug infestation, which may have reached the family's room on the first floor through a bathroom vent.

The unnamed hotel in the Fatih neighbourhood near Istanbul's historic peninsula was evacuated on Saturday after two more guests were taken to hospital with similar symptoms, Anadolu said.

The hotel was sealed off by municipal officials on Sunday, the agency added.

Among those detained were five food sellers, the hotel's owner and two staff, and three people from the pest control company, it reported, without giving a timeline for exactly when they were all detained.

Eight of them were to appear before a judge on Monday.

A toxicology report prepared by forensic experts was expected to be released later on Monday, along with a report on the food samples being checked by experts at the agriculture ministry, Anadolu added.

President Recep Tayyip Erdogan said after a cabinet meeting Monday that "our security forces and prosecutors will lead the necessary investigations to determine the causes of these deaths."

The mother and her children were buried on Saturday at a ceremony in their family village in the Bolvadin area of central Turkey, about 240 kilometres (150 miles) southwest of Ankara, several Turkish newspapers reported.