WATCH out for the plasma screen pirates, police are warning business people in York and North Yorkshire.

Conmen have been cold- calling businesses in the region offering to arrange advertising on plasma television screens mounted in public places like hospitals, schools, libraries, waiting areas, pubs, restaurants and even some buses.

Customers are asked to fill in payment details on a direct debit form. More money is taken from their banks than expected - and the advertisements never reach the screen as promised.

Detective Chief Inspector Kevin Ross, of North Yorkshire Police, said: "Complaints to the advertising companies fell on deaf ears and some people have lost several hundreds of pounds after effectively being tricked into signing bank documents."

Money taken for advertising that never appeared was a new con, he said.

People often handed over money for magazines or wall posters never published but, said Det Chief Insp Ross, this was a new 21st century variation on the theme.

He warned: "Please, only enter into a contract with companies you are satisfied will provide the advertising service they claim to be able to provide.

"Ask to be put in touch with satisfied customers, or seek independent evidence with which to satisfy yourself.

"For example, ask for details of other sites which have plasma screens fitted that you can visit to view or at least verify the facts by phone.

"Do not, under any circumstances, sign blank documents.

"Make sure you read what you sign."

Finally, he said, always ask for a written quotation for payments which can be compared with fees for legitimate services.

He said: "There are still too many fly-by-night companies which are not to be trusted."