POLICE are warning organisations in County Durham to beware of bogus cash offers.

Several organisations in the area have received letters, faxes or emails promising substantial amounts of money.

The documents, which claim to be from West Africa, usually notify businesses that an overseas investor is thinking of putting money into their company.

An offer is made to transfer millions of pounds into the recipient's bank account. The target organisation is asked for banking details or money to pay taxes, legal fees or bribes.

The effort to defraud has led the National Criminal Intelligence Service (NCIS) to create a West African Organised Crime Section.

Durham police has received dozens of faxes, letters and emails from firms in Durham City, Chester-le-Street, Teesdale and Spennymoor, which they have passed on to the NCIS.

Mark Prior, who runs a Barnard Castle art gallery, has received several emails, one of which claimed to be from Dr Olabode Johnson, of the Nigerian National Petroleum Corporation.

It promised him a 20 per cent share of more than $20m.

He said: "I don't know where these came from and I can only think they got my details from the company website," he said.

"Fortunately, I was aware of the scam and have not replied to any of the letters."

Detective Inspector Colin Gibson, head of Durham Constabulary's fraud squad, said: "We would urge people to be on their guard.

"If you receive one of these documents, do not reply, as the criminals may use your letterhead for other frauds."