This list, the second share fraud master list obtained by the FSA and CoLP in 2010, contains the names and phone numbers of about 750 people, and the names and addresses of 250. The list was discovered by the FSA and CoLP as part of Operation WARN, which was launched in February.

The letter explains what people on the list can do to protect themselves from the fraud, while phone calls from the FSA (to those on the list without addresses) offer guidance on how they can protect themselves, or what they should do if they have already invested.

The FSA will not ask for any personal details from the people on these lists, so any calls requesting personal information should be treated with caution. Anybody who has received a letter from the FSA and CoLP concerning Operation WARN, or is concerned about being a victim of share fraud can call 0300 500 5000 for further information.

Share fraudsters usually contact people by telephone and use high pressure sales tactics to con investors into buying non-tradable, overpriced or even non-existent shares. These share fraudsters, commonly know as 'boiler rooms', are unauthorised, overseas-based companies with bogus UK addresses and phone lines routed abroad.

Dealing with unauthorised firm means you do not have access to the financial complaints and compensation schemes.

Jonathan Phelan, head of the unauthorised business department at the FSA, said:

"This is the second master list we have obtained in as many months. Our sources indicate that the list is a new one and still in use by the fraudsters, so by contacting people on it we hope to cut these boiler rooms off at the pass.

"Raising awareness of this type of fraud through publicity is one of the best tools we have to prevent people getting involved and losing their money. Legitimate share dealers and brokers will not normally cold call people offering to buy or sell shares, so if you get one of these calls - just hang up and report it.

"The key message ree ressage remains: if it sounds too good to be true, it almost certainly is."

Det Chief Supt Steve Head, head of the City of London Police's Economic Crime Directorate said:

"This is the second such list we have identified in a short space of time and this is testament to both the hard work of the officers involved in these investigations and to the incredible support we continue to receive from the general public.

"Preventing people from becoming victims of these insidious criminal networks is an enormously important aspect of our work and I would like to take this opportunity to thank everyone who has contacted us to help identify them. I would also urge anyone receiving cold calls of this nature not to part with any money, and instead to contact the police or the FSA."

Shareholders and other consumers can avoid becoming victims of share fraud by:

* Hanging up the telephone if they get an 'out of the blue' call offering them shares;
* Checking that anyone offering to sell them shares is registered with the FSA;
* Calling the company back using the details on the FSA register to verify their identity; and
* Reporting any company that cold calls them to sell shares, to the FSA or the Police.

People can find further information on protecting themselves from fraud on the FSA consumer website moneymadeclear.fsa.gov.uk and The City of London Police Operation Archway website.