Unsafe chargers are about a third of the cost of safe alternatives
Hundreds of thousands of unsafe chargers for mobile phones, games consoles and music devices could have made their way into the UK.
Trading standards officers studying dangerous chargers being imported from China say vast numbers are available on the internet and in shops.
Their tests show one brand can overheat or cause electrocution.
One of the chargers concerned has the code marking DE62347066. Others have no code and are called Travel Charger.
A specific warning has already been issued about chargers for Nintendo DS and DS Lite machines, but which could also be used to charge Gameboy machines.
Trading standards officers are trying to recall the chargers.
But Chris Holden, senior trading standards officer at Buckinghamshire County Council, told the BBC that investigations were shedding light on a much bigger problem.
Some chargers carry a CE safety mark which officers believe to be fake.
"The UK appears to be flooded with them. It probably runs into hundreds of thousands or even millions," Mr Holden said.
Mr Holden said that the chargers were being sold for about £5 on the internet and about £6 in shops. Safe chargers, which have been checked properly, retail for around £15.
Officers have primarily found unsafe chargers for use with games consoles, although others are available to use with music devices and mobile phones.
Wires become detached after being used for a while leading to a risk of electric shocks. The pins do not fit properly into UK sockets causing overheating.
Numerous suppliers were bringing them into the UK, Mr Holden said.
Concerns were raised about the safety of chargers 18 months ago following the death of British boy Connor Dean O'Keeffe.
The seven-year-old was found dead by his mother on the floor of an apartment in Thailand during a holiday after using his games console charger.