A fraudster who sold more than £55m worth of fake bomb detectors to Iraq and other security hot spots has been jailed for 10 years.

Jim McCormick, 57, was found guilty of three counts of fraud over the sale of bogus explosive and drug detection devices for as much as £10,000 each when they were based on £15 novelty golf ball finders.

At the Old Bailey in London on Thursday Mr Justice Hone handed down the maximum sentence for a crime he described as "a callous confidence trick". He said the case was the most serious of its kind he has known.

After the verdict, Iraqi exiles called for compensation from at least £7m in assets that are expected to be confiscated from the Somerset-based businessman.

"He destroyed Iraqi lives," said Nidhal Ailshbib, an Iraqi activist protesting outside the Old Bailey. "Thousands of Iraqi people are dead and handicapped."

Detectives called for groups or individuals who believe they have been victims of explosions that could have been prevented if the bogus bomb detectors worked to come forward.

The judge told McCormick as he sat impassive in the dock: "Your fraudulent conduct in selling so many useless devices for simply enormous profit promoted a false sense of security and in all probability materially contributed to causing death and injury to innocent individuals."

He described how McCormick sold, with a small number of agents, 7,000 devices under the ADE brand to the Iraqi government and other international agencies for prices ranging from $2,500 (£1,600) per unit to $30,000, when they cost less than $50.

"The device was useless, the profit outrageous and your culpability as a fraudster has to be placed in the highest category," he told McCormick, who now stands to have assets worth millions of pounds confiscated.

The judge said that in terms of culpability and harm, he could imagine no more serious case.

"Soldiers, police forces, border customs officers, hotel security staff and many others trusted their lives to the overpriced devices sold by you," he said.

One of the devices, which were said to be able to detect explosives. Photograph: SWNS.com

"Your profits were obscene, funding grand houses, a greedy, extravagant lifestyle and even a yacht. You have neither insight, shame or any sense of remorse."

Prior to sentencing, the court heard statements from British army officers that bomb blasts killing civilians in Baghdad occurred after truck bombs and other explosives had passed through checkpoints manned by security officers using the fake detectors.

In a statement read out by Richard Whitam QC, prosecuting, Brigadier Simon Marriner said: "The inescapable conclusion is that devices have been detonated after passing through checkpoints. Iraqi civilians have died as a result."

In mitigation, Jonathan Laidlaw QC, defending, denied any responsibility on McCormick's part for the attacks, "any amount of protective devices at checkpoints in Baghdad couldn't protect the people of Iraq from those who conduct the insurgency there".

Mr Justice Hone refused to accept that.

A confiscation hearing under the proceeds of crime act was set for May next year. Police have warned that the fake detectors remain in use on checkpoints even though they do not work.

It is alleged by an Iraqi whistleblower that McCormick paid millions of pounds in bribes to senior Iraqis to secure the deals. General Jihad al-Jabiri, who ran the Baghdad bomb squad, is in prison on corruption charges relating to the contracts.

McCormick claimed the gadgets could detect explosives at long range, deep underground, through lead-lined rooms and multiple buildings. In fact, their antennae, which appeared to be like car radio aerials, were not connected to any electronics and had no power source.

McCormick's first model, the ADE-101, was a re-badged golf ball finder that was described by its US maker as "a great novelty item that you should have fun with".

The antenna was "no more a radio antenna than a nine-inch nail", one scientist told the jury.