George Jack Temperley-Wells is thought to have travelled from Darlington with his mother.
Police in the UK are appealing for urgent help in finding a four-year-old boy believed to be in Turkey.
George Jack Temperley-Wells is thought to have travelled to the country from Darlington on 29 June with his mother, Brogan Elizabeth Temperley.
He was last seen in the marina area of Antalya, a resort on the south coast.
Durham Police said officers had “serious concerns” for his welfare and needed to find him and speak to his mother.
“Anyone who is in contact with her is asked to encourage her to contact the authorities in Turkey or the UK immediately to confirm her whereabouts and/or seek assistance to return home,” a spokesperson said.
George is described as having red hair, a pale complexion and dark eyes.
Ms Temperley, 28, is said to be slim, with long, dark hair and dark eyes.
They are likely to have spent time in Turkey with the four-year-old’s father, 41-year-old Scott Nigel Wells, police said.
Anyone with information is asked to contact Durham Constabulary on 101 or, if in Turkey, to visit a local police station or call the country’s emergency number on 112 or 115.