More than 30 businesses in the north-east were visited by Trading Standards officers as part of an operation.
Aberdeenshire Council visited firms in Fraserburgh, Peterhead, Stonehaven, Portlethen and Inverurie as part of Trading Standards week.
Inspectors from the weights and measures teams were checking pre-packaged goods complied with regulations.
More than 400 products were tested, including meats, biscuits, ready meals and cakes.
It is an offence to sell pre-packed items below the advertised weight, which is known as the catchweight.
Officers at Aberdeenshire Trading Standards visited licensed premises, independent stores and large shops and found 20 items were non-compliant for reasons including not being the advertised weight, and having incorrect labelling.
A spokesman for Aberdeenshire Council said: “It is an offence to supply a catchweight product less than the stated quantity.
“The worst offending item was found to be 52g below the stated quantity.
“Further action will include referral to the local authority of the packer, advisory visits to local packers, investigation of importers and advice to local retailers.”
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Meanwhile, in Aberdeen, a two-day operation was carried out with council licensing officers and Police Scotland.
Inspectors made 16 visits to alleged unlicensed car traders selling second-hand vehicles in a bid to clamp down on illegal trading.
Advice was given to traders and licensing officers have been informed that since the operation, three of those visited have now become licensed dealers.
PC Sean Fyffe, from the north-east division, said: “As part of the established and collaborative work between the service and Trading Standards Scotland, advice was offered to individuals with regards to becoming officially licensed to trade in vehicles.”