The painstaking work of removing deteriorating crates of dangerous First World War chemical weapons is underway near Vimy, France - the site of one of Canadaās greatest military triumphs.

Now that most area residents have been safely evacuated, a convoy of refrigerator trucks are carefully transporting 170 tons of potentially volatile shells to an army base in northern France. The shells - which include ones containing mustard gas - are less likely to explode if kept cold.

Already, small amounts of highly toxic gas has leaked out of one of the thousands of shells as it was being carried out, said a military spokesperson. Removal teams put on protective clothing and continued the operation. No one was hurt.

The chemicals and explosives being removed make up about half of the munitions stored at the Vimy stockpile.

PRECAUTIONARY EVACUATION

Nearly 13,000 people in a three kilometre radius of the stockpile have been told to leave the area. Officials said it could be as long as 10 days before itās safe for them to go home.

Many of Vimy's 4,500 residents spent the night in hotels or nearby school dormitories, but a few have refused to leave their homes, despite efforts to persuade them to do so.

Although residents agree the munitions removal is timely and wise, some are angry at the last minute decision to evacuate the area.

Before the moving job began, authorities feared some of the ancient munitions could explode or leak toxic chemicals if not taken away properly.

A TURBULENT PAST

Vimy Ridge was the site of a Canadian assault on German forces in 1917 that resulted in the deaths of more than 200,000 soldiers.

For Canada, the attack on Vimy Ridge marked a turning-point in the country's march towards nationhood.

Today, the Vimy depot is the main storage site for a First World War bomb-hunting team that receives thousands of calls each year to collect stray weapons.

In Vimy and the surrounding area alone, more than 100 tons of unexploded wartime shells turn up each year.