French army experts have begun repair work on a volatile stockpile of deadly World War One chemical weapons and munitions after evacuating 12,000 people from the town of Vimy in northern France.
Police, accompanied by psychologists, attempted to convince a few dozen recalcitrants to quit homes and farms within a two mile exclusion zone.
Firemen ringed the site with water-spraying equipment, ready to throw up a wall of water to contain any leaks of the highly toxic chemicals that the disposal experts were set to tackle as soon as they got final word that the exclusion zone was empty.
The risk is minimal, said Yvan Consul, the man in charge of a delicate and arduous clean-up operation which is expected to last 10 days."We will start by securing HLM2 munitions, the shells containing toxic substances," he said.Some 173 tonnes of bombs, shells and mines are stacked at the depot in Vimy, site of a bloody Canadian assault on German trenches at Easter 1917.
Most of the residents of Vimy were housed in schools and holiday camps further away from the site.
The French Interior Ministry says a recent survey of the compound showed the munitions were in a dangerous state of repair, with some of the crates of shells splitting apart.
The stockpile is thought to contain shells of mustard gas, the most lethal of all poisonous chemicals used in the 1914-1918 war. Mustard gas causes internal bleeding, blindness and slowly destroys victims' lungs.
Bomb disposal experts were set to relieve each other in small groups and were only allowed to work for limited periods because of the danger of the chemicals.
Piles of crates containing the deadly munitions would be unloaded one-by-one into cold storage trucks where temperatures of between zero and minus two degrees centigrade would help to reduce the risk of evaporation, he said.
The risky munitions would be transported to a military compound once the eight trucks involved in the operation were full, he added.
Vimy has served for more than a quarter of a century as one of the main depots for munitions from the two world wars which are regularly discovered in the fields and near the beaches of northern France.
The French Health Minister, Bernard Kouchner, arrived in Vimy shortly before midday.
The government decided in 1997 that the compound should be closed and the sudden move on Friday to do the job in a hurry angered residents who were given just hours to quit the danger zone.
Two bomb disposal experts were killed in Vimy in 1998 after one of the shells exploded.
The clean-up was expected to get going in earnest once the emergency services got final word from the local prefect that the exclusion zone was fully secured.
"Around 30 people have refused to move. If they do not understand I will have to take action", said Jean Dussourd, the prefect for the Pas-de-Calais, the region that includes Vimy.