Concerns for a British ship torpedoed by the Nazis near Bell Island, Canada, in 1942 has prompted the Canadian navy to take action.

The SS Saganaga was sunk along with three other vessels by German U-boats during World War II, killing dozens of crew members.

But lives weren't all that was lost - aboard each vessel, the Canadian navy believes there were also up to 60 highly-explosive shells, as many as 240 in total.

Concerns for a British ship torpedoed by the Nazis near Bell Island, Canada, in 1942 has prompted the Canadian navy to take action

The SS Saganaga was sunk along with three other vessels by German U-boats during World War II, killing dozens of crew members

But lives weren't all that was lost - aboard each vessel, the Canadian navy believes there were also up to 60 highly-explosive shells, as many as 240 in total

Fears that the sunken shells could present a ticking time bomb as they decay have prompted the Canadian navy to launch the delicate operation of dispatching divers down to the wrecks to bring each shell to safety.

The operation is now underway and is expected to conclude by Thursday.

Lieutenant Tim Woodworth said: 'The expected ordnance sizes are 4-inch and 4.7-inch naval projectiles. Two ships had 4.7-inch guns; the other two had 4-inch guns.

'Based on historical information, it is estimated there could be about 50 to 60 rounds per ship.'

Civilian diver Neil Burgess, president of the Newfoundland and Labrador Shipwreck Preservation Society, said the ships were targeted by the Nazis because of their cargo.

'The ships were hauling iron ore from Bell Island, Newfoundland, to the steel mills in Sydney, Nova Scotia,' he said.

'The steel produced at Sydney was vital to the Canadian war effort.'

Fears that the sunken shells could present a ticking time bomb as they decay have prompted the Canadian navy to launch the delicate operation of dispatching divers down to the wrecks to bring each shell to safety

Lieutenant Tim Woodworth said: 'The expected ordnance sizes are 4-inch and 4.7-inch naval projectiles. Two ships had 4.7-inch guns; the other two had 4-inch guns. Based on historical information, it is estimated there could be about 50 to 60 rounds per ship.'

'The ships were hauling iron ore from Bell Island, Newfoundland, to the steel mills in Sydney, Nova Scotia,' he said

He continued: 'Each of the ships was equipped with a stern gun to defend against submarines on the surface.

'Each ship carried high-explosive artillery shells for the stern gun. Those shells are now being removed by the Canadian navy divers.'

Alongside Britain's Saganaga, the divers will also remove munitions from France's PLM 27, and the Lord Strathcona and Rose Castle - both from Canada.

The wrecks have become popular dive sites and some visitors have encountered the remaining explosives.

'Recreational divers have found shells lying on the decks of several of the ships in recent years,' said Neil. 'These posed a hazard to divers.'

Each shell has to be carefully loaded into a net to be hoisted to the surface

If they dry out, they can explode, so they're then wrapped in blankets and doused with water to keep them wet until they can be safely destroyed

The SS Saganaga (pictured) was sunk along with three other vessels by German U-boats during World War II

'The Navy wanted to make the wrecks safe for recreational divers to explore.

'As the steel shipwrecks rust and collapse, things like the shells become exposed as steel lockers fall apart.'

Each shell has to be carefully loaded into a net to be hoisted to the surface.

If they dry out, they can explode, so they're then wrapped in blankets and doused with water to keep them wet until they can be safely destroyed.

However, the navy expects it wont be able to completely clear the wrecks of munitions.

Lieutenant Zach Johnson told Canada's public broadcaster, CBC, that some bombs would remain beyond their reach.

'There are some that end up, just due to the nature of the degradation, possibly buried 10 feet under five collapsed decks that we can't get to,' he said.

The operation is now underway and is expected to conclude by Thursday.

29 Brits lost their lives when the Saganaga was torpedoed by the U-513 on September 5, 1942.

Between 24 and 29 men were killed aboard the Rose Castle, while 12 sailors - mostly French and a few Canadians - were lost from the PLM 27.