Postwar Germany began its second biggest evacuation of a major city on Sunday as ordnance disposal experts moved in to Hanover to tackle five RAF bombs from World War II found on building sites.

Fifty thousand people from flats, houses, care homes and clinics were on the move in Hanover at 9.00am and told they won't be allowed back for up to 24 hours. The number amounts to ten per cent of the city's population.

Hanover was hit 125 times by Allied air forces during the war. The unstable duds that must be tackled date from a raid in October 1943 when 260,000 high explosive and incendiary devices were dropped.

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These are the World War II bombs discovered on a building site that led to the evacuation of 50,000 people in Hanover including residents of seven care homes

Fifty thousand people from flats, houses, care homes and clinics were on the move in Hanover at 9.00am on Sunday

The evacuation came after five RAF unexploded RAF bombs from World War II were found on a building site

The bombs were from a raid in October 1943 when 260,000 high explosive and incendiary devices were dropped.

The raid killed 1,245 locals and left a further 250,000 homeless.

Hanover was often a target for Allied forces in World War II. It was a vital railway junction through which two major east-west and north-south routes passed.

Additionally, it was an industrial city where tyres for military vehicles and aircraft were produced.

Tyres were made by Continental AG factories in Hanover, while another factory - run by Accumulatoren Fabrik Aktiengesellschaf (AFA) - built batteries for submarines and torpedoes.

The Hanover evacuation was only topped by a mass movement of people in Augsburg on Christmas Eve last year when 54,000 people were forced from their homes by unexplored wartime bombs.

The raid in which the newly discovered bombs were dropped killed 1,245 locals and left a further 250,000 homeless in Hanover. Pictured above, the building site where the RAF bombs were found

The Hanover evacuation was only topped by a mass movement of people in Augsburg on Christmas Eve last year when 54,000 people were forced from their homes by unexplored wartime bombs. Pictured above, the building site where the RAF bombs were found

Schools have been opened to accommodate those with nowhere to go. Long distance trains have been rerouted to avoid the city's main train station

The city has launched a number of cultural and athletic activities for those affected by the evacuation to keep them busy

The 'iron harvest' of bombs and munitions continues to be a huge headache for Germany 72 years after the end of the war

Thousands of helpers from across the state of Lower Saxony have been drafted in to aid in the Hanover evacuation.

Schools have been opened to accommodate those with nowhere to go. Long distance trains have been rerouted to avoid the city's main train station.

The evacuation zone included seven care homes, a hospital and a tyre factory. Residents are expected to be able to return to their homes in 24 hours.

The 'iron harvest' of bombs and munitions continues to be a huge headache for Germany 72 years after the end of the war.

It is estimated that 150,000 bombs lie unexploded beneath German towns and cities and they grow more unstable with every passing day.

Elderly people from a senior care facility wait to board a bus as part of the evacuation of 50,000 people on Saturday

Bomb disposal experts will check five locations in the city today where unexploded bombs from World War II lie underground

Unexploded World War II bombs, mostly from Allied aerial bombing, remain a deadly legacy and smaller scale evacuations are a regular occurrence in major urban centers across Germany throughout the year

Dozens have been killed and injured in explosions in the past decades and thousands placed in danger.

In 2011, falling water levels on the River Rhine in Koblenz exposed two mammoth RAF bombs capable of causing catastrophic damage if they detonated: Some 45,000 people were evacuated to render them safe.

A bomb from an RAF or US Air Force plane from WWII is discovered on average once a day across the country, sometimes as many as three times a day, costing authorities tens of millions of pounds a year.

The Allies rained 2.7 million tons of bombs on Germany between 1940 and 1944.

The academic Journal of Mine Action estimates that as much as half of them failed to do their job.

Thousands of helpers from across the state of Lower Saxony have been drafted in to aid in the Hanover evacuation

It is estimated that 150,000 bombs lie unexploded beneath German towns and cities and they grow more unstable with every passing day

Dozens have been killed and injured in explosions in the past decades and thousands placed in danger. Pictured above, elderly people are evacuated from a care home on Sunday

Many of these bombs are of a type containing a vial of acetone in the fuse which was designed to burst on impact.

The fluid was meant to trickle down and dissolve a celluloid disk keeping back the cocked firing pin that then ignites the TNT inside.

Those components, as well as the plastic parts of other detonators, are disintegrating at an alarming rate.

Experts warn that within a decade bombs will begin to detonate by themselves - or will be too unstable to defuse if discovered.

That would mean controlled explosions on site with colossal damage to infrastructure around and about.