A large World War II bomb was successfully defused by Greek authorities after a mass evacuation of tens of thousands from the country's second largest city, Thessaloniki.

The unexploded bomb was discovered about five meters (16 feet) underground near a gasoline station during road works last week.

"The operation is over, everything went well," regional security chief Apostolos Tzitzikostas said four hours after a demining team began its work.

He subsequently tweeted in Greek, "Phase two of the bomb removal operation was successfully completed. Citizens can safely return to their homes." 

In the end it took Greek army soldiers just 30 minutes to defuse the 1.5-meter-long bomb that was packed with about 170 kilograms (375 pounds) of explosives, a bit smaller than officials first believed.

The bomb's firing mechanism "was still in a very good shape, and this was what had us worried," army chief of staff Nikos Phanios said.

A British warplane dropped the American-made bomb during airstrikes on the city's nearby railway station and port in 1943 or 1944. The attack killed hundreds of local inhabitants, according to Greek media reports.

The start of Sunday's operation was delayed because police stopped to remove a camera that had been placed above the crater by a Greek media outlet.

An unprecedented operation

More than 70,000 people were evacuated within a 2-kilometer (1.2-mile) radius of the site, affecting three working-class neighborhoods west of the city center.

The operation was unprecedented in Greece, "where a bomb of this size has never been found in an area this densely populated," Tzitzikostas said. He praised the population for its discipline.

Many locals were inconvenienced by the bomb and the forced evacuation. But for a group of refugees, among the evacuees, it was an opportunity to get out of their camp.

For one group of refugees and migrants, the discovery of the bomb led to an excursion to a museum.

Many of the refugees, most of whom are fleeing Syria's civil war, live in a nearby former toilet paper factory. About 450 people live in the Softex refugee camp in an industrial zone on the outskirts of the city, in conditions described as "prison-like" by Amnesty International.

They are among about 60,000 refugees and migrants stranded in makeshift and formal camps across Greece since Balkan countries closed their borders almost a year ago to those seeking passage to western and northern Europe.

bik/jlw  (AP, Reuters, AFP, dpa)