DEFENCE chiefs are being urged to give assurances they are monitoring potentially dangerous unexploded wartime bombs in the River Clyde and that nuclear submarines based at Faslane will not disturb them.

The call is being made by Inverclyde MP Ronnie Cowan who is due to put his concerns to Defence Procurement Minister Philip Dunne next month.

Cowan arranged the meeting after dozens of his constituents were evacuated from their homes in Gourock last year after a sea mine was found by divers off the town.

Following the incident, the SNP MP raised questions about how the aerial bombardment of the Lower Clyde continued to impact on the area and was told by the Ministry of Defence (MoD) that only 20 per cent of the bombs dropped along the UK coast had been accounted for.

“Scotland deserves better than the UK Government’s relaxed attitude towards our maritime safety, especially when submarines carrying up to 40 nuclear warheads routinely pass our shore on the way to Faslane,” said Cowan.

“Vague assurances are not enough, and we still don’t know how much unexploded munitions could still be in the Clyde, and what procedures the UK Government has in place to monitor and dispose of unexploded ordnance before it becomes a problem.”

He added: “I will use my upcoming meeting with the MoD to press for further detail and assurances that the UK Government is taking this issue seriously.

“The revelation that only 20 per cent of the ordnance dumped in the sea has ever been accounted for is serious cause for concern.

“The sea mine found near Gourock last year shows that unexploded ordnance can still pose a serious threat to shipping in the area.”

Hundreds of thousands of bombs were dropped on Britain in the Second World War.

They are regularly found, often leading to an evacuation of the area before the bomb is safely defused in a controlled explosion.

Last year Matt Brosnan, a historian at the Imperial War Museum, said it was impossible to know exactly how many devices were undiscovered.

“Just to put it in context, the Luftwaffe dropped 24,000 tonnes of high explosive on London in 85 major raids during the war,” he said.

“Clearly not all of those would have exploded, because of defects or other reasons, and they could have buried themselves [below] the surface so we simply don’t know where they are.”

Brosnan said that the bombs are unlikely to explode, but their threat should not be underestimated.

“The risk is in their unpredictability, they are inherently unstable and still contain explosives, which is why they are treated so seriously and have to be disposed of properly and safely,” he added last year.

The largest bombs dropped on Britain were almost 4,000lb (1,800kg) devices nicknamed Satans.

“I think the cordons put in place today give you an idea of how wide the damage could be,” said Brosnan.

“They would destroy buildings, make them totally uninhabitable, not to mention lives that would be lost.”

Glasgow, Greenock and Clydebank were among the places targeted by the Luftwaffe.

A cordon of 200 metres was set up in Gourock last year after the unexploded mine was found off Gourock.

People living 500m from the detonation site were warned not to stand beside the windows because of fears over the size of the blast.

A guide on dealing with unexploded devices was released by the Construction Industry Research and Information Association (CIRIA) in 2009.

The CIRIA guide said as well as posing a risk, the discovery of unexploded devices can have “significant implications” for builders, causing delays and an increase in costs.

Last night an MoD spokesman said: “The Department places the safety of our nuclear fleet at the highest possible level and there are continuous attempts to ensure that any potential threats to our submarines are monitored.”