Thousands of residents of the second-biggest Greek city of Thessaloniki were evacuated earlier today to allow experts to defuse a World War Two bomb.

According to Reuters, the 250 kg bomb was discovered about 5 metres below ground during excavation works at a petrol station last week. Up to 72,000 residents living within a 2 km radius of the bomb site were asked to leave their homes in one of the country's biggest peacetime evacuations. Buses were taking them to local gyms, stadiums and cafes.

Refugees and migrants living in a camp in a nearby abandoned factory are also be evacuated today and taken on a museum visit in Thessaloniki, the migration ministry said.

Military experts will attempt to defuse the bomb on the spot. "We are absolutely ready," Regional Governor, Apostolos Tzitzikostas, told Greek TV before the operation began.

He added, "I call on our fellow citizens to stay calm. There is no reason to panic, there is no danger, the measures taken are precautionary and for the safety of residents." The complex operation was expected to last at most six hours.