They claim it happened near the Evros river, which flows for more than 150km from Bulgaria to the Mediterranean Sea.
The Greek police have denied the allegations.
Al Jazeera's Laurence Lee reports from northern Greece.
Russian-Saudi relations could be very different today, if Stalin hadn't killed the Soviet ambassador to Saudi Arabia.
Answer as many correct questions as you can and see where your country ranks in the global cost of living.
Journalist John Pilger on how the world's greatest military power, the US, may well be on the road to war with China.