More than 50,000 people have been ordered to leave their homes in Hanover, Germany, ahead of a large-scale operation to defuse unexploded bombs dating back to World War II, according to officials.

A total of 13 unexploded ordnances from the 1940s, found at a construction site, are expected to be removed from the northwestern city on Sunday. Defusing operations will start in the morning, but may last well into the night.

The evacuation, the second-biggest since 1945, involves three heavily-populated areas of Hanover, which account for 10 percent of the city's entire population.

Early evacuations started on Friday and Saturday as residents of senior care facilities were relocated to other parts of the city.

City authorities have announced restrictions on movement for security purposes.

Trains, for example, will not stop at Hanover's main station, prompting users to engage in online dialogues with representatives of local rail services in order to plan their day.

@DB_Bahn Sehe ich das richtig, das diese Verbindung morgen von der Bombenentschärfung in #Hannover nicht betroffen ist? pic.twitter.com/WvZJtsvQhB — Helma (@phelmas) May 6, 2017

Museums, cinemas and swimming pools are offering special, mostly free, programmes for those evacuated.

One museum, for instance, is charging no admittance fee for the exhibition "What remains of Palmyra? Syria's destroyed heritage".

WWII bombs

Such evacuations are not uncommon for Germans and construction sites seldom run without stumbling upon unexploded bombs from World War II.

German authorities are under pressure to remove unexploded ordnance from populated areas, with experts arguing that the bombs are becoming more dangerous as time goes by due to material fatigue.

Last year, the country organised its biggest evacuation to date with 54,000 people relocated in southern Augsburg.

Hanover was a frequent target of Allied bombing in the latter years of the war. On October 9, 1943, some 261,000 bombs were dropped on the city.

Some Twitter users were impressed that news of the Hanover operation had made it to New Zealand and Indonesia.

In #Hannover steht eine Evakuierung an und auch in #Neuseeland und #Indonsien weiß man Bescheid. #hannbombe @nzherald @SINDOnews https://t.co/HNAIDHUM5q

— Linda Tonn (@linda_tonn) May 6, 2017