Undercover Investigators have started work on trying to crack down on loan sharks in Scotland.
Illegal money lenders prey on the poorest in society
It is thought that about 100 illegal money lenders operate throughout the country, giving out cash loans to desperate people.
They then use threats and violence to extort huge sums in return.
Money advisers said that, although they are well aware of loan sharks, the people they see often will not speak about who they owe money to.
Experts said borrowers claim they simply owe money to a friend, because fear of reprisal forces them to keep silent.
Illegal money lenders often take benefit books and use threats against a victim's property - and even their children - to make sure they are paid their cash.
One victim said: "I went to the money lenders because I thought at first that if I get something off them, it will pay some of the debt.
"I had not actually thought of them as money lenders. They'd be chapping on the door and asking if we wanted loans."
She added: "I thought it was a really good idea because they were going to give me this money and it didn't matter how much I earned.
"They would give it to me anyway and come every week for the money, but I was hounded for three years by the money lenders."
Vincent Chuddy, of the Glasgow Central Citizens Advice Bureau, stressed that people were frequently more keen to pay back criminal loan sharks, than high street banks.
"Very often it starts as threats, such as looking for exorbitant amounts of money to be paid back for the amount they've borrowed," he said.
"Then attacking their property, attacking themselves and - worst of all - attacking their children. Threats such as they will break the children's legs."
The crackdown involving the Scottish Illegal Money Lending Team is a joint initiative involving the Department of Trade and Industry (DTI) and the national crime-fighting service Crimestoppers.
People can contact the Crimestoppers hotline with information and the specialist team, which will be based in Glasgow, will cover the whole of Scotland.
The eight-strong hit squad includes former police officers and will work underground to hunt down the protection racket gangs.
Scotland's largest city, where the problem is bigger than in many other parts of the UK, is only the second place to be chosen for the trial shark-hunt project.
Although money advice agencies welcome the crackdown, some doubt investigators will persuade victims - described as the "lowest section of the financial community" - to "grass up" the sharks.
Illegal money lenders prey on the poorest areas
Mr Chuddy argued: "It will only work if the public actually come forward and report the illegal activities to the police and trading standards. Up till now they are very reluctant to do so."
Critics also say action is equally needed to clamp down on legitimate companies who charge exorbitant rates of interest, often sending people deeper into debt.
John Milligan, of the Vale of Leven Credit Union, highlighted a case where a doorstep lending company demanded a £990 payback on a £600 loan.
"They are people who come to your door and present you with cheques. They don't charge interest - it's a service charge - and it's astronomical.
"People think it's well within their budget at the time, but it's obviously not."
Victims of loan sharks can contact Crimestoppers on 0800 555 111.