The introduction of congestion charging in Edinburgh could hit the profits of retailers in the city centre, an independent report has found.
Many retailers in Edinburgh have opposed the charges
It predicts a 4% reduction in sales over seven days unless there are improvements in public transport and an effective marketing campaign.
The study comprised three surveys on shoppers' intentions.
A referendum on the introduction of road tolls will be held early next year.
Plans include charging drivers £2 per day to cross one of two cordons.
The council wants two cordons, one inside the capital's ring road, the other round the city centre.
The charge would apply from 0700 -1830 at the inner cordon and 0700- 1000 at the outer boundary on weekdays.
Motorists would only be charged once each day and would not have to pay extra for crossing both cordons.
Gordon Reid, chief executive of Edinburgh City Centre Management Company Ltd, said the report "doesn't pull any punches".
"It makes it clear that congestion charging is a challenge for city centre retailers, but offers evidence that any negative impact can be overcome," he said.
"The impact is potentially manageable, but indicates the necessity to deliver the rest of the transport improvements and keep customers fully informed about them if retailers are not to lose out."
Mr Reid said the company was liaising with the council to ensure the city remained "a premier retail environment".
Robert Winter, of the City Centre Retail Group, said: "Retailers large and small across the city centre remain concerned about the potential impact of congestion charging on their sales.
Edinburgh's traffic jams have caused a collective travel headache
"No retailer can afford to lose 4% in sales over seven days or, as the report states, 7% of retail sales activity during Monday to Friday, which is the planned charging period."
Mr Winter said if the council decided to proceed with congestion charging, it would have to help retailers cushion the blow.
The Scottish Retail Consortium (SRC) said the report's findings made "interesting reading".
SRC director Fiona Moriarty said a 4% fall in sales could hurt retailers, but she urged them to work with the council to ensure this could be avoided.
"Now is the time for retailers to work in partnership with the city council and other agencies to start marketing the extremely positive strengths of Edinburgh city centre to offset any potential short-term damage caused by the congestion charge," she added.
Scottish Enterprise Edinburgh and Lothian said it was committed to creating "a vibrant, modern European capital city".
Chief executive Jim McFarlane said it was important to tackle the city's transport issues and improve its infrastructure.
"As this report indicates, short-term pain will give way to long-term gain with everyone working together to create a modern, world-class city centre environment," he stated.
Earlier this year, First Minister Jack McConnell said he was "very impressed" with the scheme currently being used in London and that Scotland would have to face up to the issue at some point.