Consumers in the north of Scotland are paying up to 50% more for parcel deliveries compared to the rest of the country, research has found.
A report by Citizens Advice Scotland (CAS) found those living in northern and north eastern parts of the country pay at least 30% more on average for delivery charges than consumers elsewhere in Britain.
The figure rises to 50% more on average in the Scottish islands.
CAS said the issue affects anyone ordering goods to be delivered north of the central belt, including those in Perth and Kinross, Aberdeenshire, Argyll and Bute, the north west Highlands and the islands.
The organisation has called on parcel companies to consider collaborating with each other and the public sector to reduce their operating costs, and therefore drive down delivery charges for consumers.
Its research looked at delivery options for a range of online purchases to 12 addresses representing various areas of the UK - including urban and rural, mainland and island.
The standard or economy delivery option was used to calculate average prices.
It found that, for smaller parcels, consumers in the north of Scotland face delivery prices about 13% higher than for urban consumers in the rest of Britain.
'This new data is stark and shows that people in the northern half of Scotland are hit by delivery surcharges which can be difficult to justify.'Nina Ballantyne
For larger parcel sizes, the average delivery cost was 23% higher while in the heavier weight category of 20kg to 30kg it was significantly more than double the cost.
For the heaviest items, costs can rise to almost four times as much as for the rest of Great Britain.
CAS consumer spokeswoman Nina Ballantyne said: "This new data is stark and shows that people in the northern half of Scotland are hit by delivery surcharges which can be difficult to justify.
"This is not just a problem for remote and rural areas.
"The areas affected include Perthshire, Moray, Aberdeenshire and Aberdeen City, as well as the Highlands and Islands."
She also said many online retailers are "not transparent" about the charges which means consumers cannot make informed choices.
Ms Ballantyne added: "We believe that any delivery charges should be up front and justifiable, and would like to see consistent pricing policies across the UK.
"We are committed to finding solutions for consumers and are working with delivery companies and other consumer groups to reduce delivery costs and improve transparency.
"We hope to identify suitable trial projects in the coming year, in partnership with the Scottish Government, local authorities and communities."
The report was published ahead of a debate on the issue at Holyrood on Tuesday.