The FSA is contacting thousands of people to warn them they could become share fraud victims following the recovery of the biggest ever ‘master list’ used by so-called ‘boiler room’ fraudsters.

The list contains the names, addresses and telephone numbers of 49,387 people and includes potential victims who the FSA believes may have been contacted out of the blue and offered worthless shares.

The greatest concentration of targets is in London, although there are a significant number based in Scotland and the South East of England. The list is thought to still be in use by fraudsters operating in the UK and abroad and is likely to have been circulated between different boiler room networks.

The FSA is writing to every single person on the list to alert them to their presence on it and to advise them how to avoid getting scammed.

Anybody who thinks they may have been targeted by a boiler room scam should call the FSA’s customer contact centre on 0845 606 1234.

Margaret Cole , the FSA’s managing director of enforcement and financial crime, said: “So far this year we have contacted 95