Aviation data company Cirium said Istanbul had seen 416 cancellations on Sunday and Monday, with Athens having 116 cancellations on Monday. 

In total, 943 flights were cancelled across Greece and Turkey on Sunday and Monday.

Athens airport showed several cancellations on Monday, however, an official notice said: “Following an intense snowfall at the airport and in the wider Attica region since the morning hours of 24 January, operations at the airport remained, and still are, normal while weather is now gradually improving.”

Both Athens and Istanbul have access issues due to snow disrupting road and rail links. Temperatures in Greece are reported to have fallen overnight to -14C.

An Istanbul airport spokesperson told Reuters on Monday that limited flights had begun around 1pm UK time after a 22-hour delay, while scheduled flights would resume around midnight.

Turkish Airlines said it had halted all flights until 9pm UK time.