Small businesses in the UK were today urged by the Office of Fair Trading (OFT) to hang up on cold calling telephone sales scams selling advertising in publications that claim to support emergency services or charities.

OFT and trading standards services across the country have received hundreds of complaints from businesses about the tactics of some telesales companies.

Reported problems included sales staff making false claims about links to the emergency services or charitable organisations.

OFT added that it is also concerned about false claims that businesses have already agreed to buy advertising space, and demands for payment when no such agreements have been made.

The watchdog advised UK workers not to take unsolicited calls when they are busy, and not to agree to something on the phone just to get rid of a persistent caller as legally binding agreements can be made over the phone.

Firms were also advised to be wary of unsolicited callers suggesting or implying that you are placing an order or entering an agreement when you do not wish to do so.

OFT chairman Sir John Vickers said: "Small businesses are particularly vulnerable to these types of unfair business practice. We advise all businesses to be wary: don't be pressured or tricked into agreeing to advertising you don't want or into paying for something you haven't requested."

The Trading Standards Institute (TSI) said that it shares OFT's concerns. Ron Gainsford, the TSI chief executive, said: "This is particularly timely and sound advice from the OFT.

"Trading Standards is increasingly alarmed by the lengths to which some cold-calling telesales operations will go to get well meaning consumers and businesses to part with their hard earned money."

OFT said it is considering "a number of complaints about misleading claims and will take enforcement action against those who make them where appropriate".