The island, which is just five miles long and nine miles wide, is a British crown dependency and uses British Sterling, but is self-governing. There are less than 50,000 private dwellings on the island, according to the 2021 census, and just 4,000 were declared to be vacant.
The average cost of a home in Jersey, £666,000, is more than two times the average cost of a house in the UK.
Following a peak in 2022, house prices on the island have begun to fall, according to the Jersey House Price Index, dropping by 2pc in the year ending in the final quarter of 2023 compared to the same period in 2022.
The index found that the turnover of properties was down 36pc in the last quarter of 2023 compared to 2022, although the market was showing some signs of recovery, with new builds proving to be particularly popular.
Mortgage rates in the Channel Islands usually follow the Bank of England rate, the consumer council’s letter said.
Following 14 consecutive rises from December 2021, the Bank Rate has sat at 5.25pc since August, with the next decision to come on March 21.
An HSBC spokesman said: “We can confirm that we have received the letter from the Jersey Consumer Council regarding Channel Island mortgage rates, and we will be replying to them in due course.
“HSBC UK and HSBC Channel Islands and Isle of Man are two separate businesses, legal entities and jurisdictions, which take into account a number of different factors when offering mortgage rates to our customers.”
An RBS International spokesman said: “Our mortgages are priced according to local market conditions, taking into account affordability, operating costs and credit risks.”
All other banks in question were contacted for comment.