£30,000

antiques and works of art because of the commission fees imposed by auction houses.

It fears the estimated prices in auction catalogues could be misleading, as they do not state the premium that is charged to buyers. This is typically 20 per cent on top of the bid price.

The issue has left auctioneers at loggerheads with antiques dealers – who, as retailers, already have to sell items with a total price.

One leading auction house body has described the investigation as potentially “mischievous”, while a leading antiques dealer said it was long overdue.

Some auctioneers fear that, if the premium has to be incorporated into the estimated value, the higher prices will drive away buyers.

The ASA opened its investigation after receiving just