TRADING standards bosses are warning businesses of a new fax scam originating from the India sub-continent.

They were alerted to the problem when a North Yorkshire school reported that it had received a fax headed with the words "Fax Back".

In the text the document stated that their fax number had been obtained and they wished to sell the number on to various fax advertising agencies located outside the European Union.

The recipient was invited to fax back to the sender refusing permission for their number to be sold on - but the catch was that the cost of sending the fax back was £3 on a premium rate number.

Carl Les, North Yorkshire's executive member for trading standards, said: "This is the latest of many similar scams involving premium rate numbers. There is really very little we can do to stop them, but consumers and businesses can help protect themselves.

"They can register with the Fax Preference Service, but unfortunately this will not stop problems from abroad. At the same time, you can also register with the telephone and postal preference schemes.

"You can block outgoing callers and faxes to premium rate numbers - most telephone companies offer this service, including BT and most are free. Be vigilant and keep an eye out for 090 premium rate numbers."

Call blocking and preference schemes can be accessed through the Trading Standards Institute website www.tradingstandards.gov.uk

Anyone who receives a similar fax is asked to call 0845 330 3313.