Consultants Oxera said that the UK-oriented nature of Jersey's economy - in particular its retail sector - meant that pumping cash into a more frequent ferry service between Jersey and France could not be justified on economic grounds.
At present there is a twice-daily ferry service between the UK and Jersey, six days a week, which carries food and other goods. But there is only a weekly service between the island and France, even though France is closer to Jersey than England. Speculation has been growing for some time that the government is poised to grant permission for a new supermarket development on the island.
In the past 18 months officials have been in talks not only with the major UK multiples, but also France's Carrefour and discounters Aldi, Netto and Lidl.
Last month ministers agreed a planning policy to clear the way for a new supermarket development, bringing the prospect of a new store ever closer.
Jersey's retail scene is dominated by retailers with British supply chains, with just a handful of full-size supermarkets on the island run by Channel Islands
Co-operative and CI Traders, which runs Checkers stores and the Safeway on the island. Other food retailers in Jersey include Marks and Spencer and Spar.
There is concern among some that there is not enough competition in Jersey's grocery sector, with experts claiming that supermarkets on the island are overtrading compared with UK counterparts.
The Oxera report said: "Increasing trade with France is unlikely to deliver significant overall economic benefits to the island. It is not a panacea that would deal with the relatively high prices on the island. There is no general economic case for government intervention to sustain a freight ferry service to France."
Kevin Keen, president of the Jersey Chamber of Commerce, which opposes the building of a new supermarket, said: "This does not bode well for a French supermarket."