South West water bills are amongst the highest in the country

Prices in the region are the highest in the country - about 75% higher than the national average.

Minister Jim Knight said equalising prices would overturn the framework of regulation, and could weaken South West Water's resolve to keep costs down.

A Commons debate on Tuesday followed calls from the region's MPs for help.

Pilot study

Mr Knight, Minister for Rural Affairs, Landscape and Biodiversity at the Department for Environment, Food and Rural Affairs (Defra), said help through the benefits system would not work in just one area of the country.

He said solutions being put forward by MPs, including equalisation, were not the answer.

The Water Charges Equalisation Act 1977 sought to equalise water charges across England and Wales, but the act was repealed around the time of water privatisation in the late 1980s.

Mr Knight told the Commons: "I am not yet persuaded that it would be right to subsidise South West Water's investment, either through a national fund drawing money from all water companies, or by public subsidy from taxation."

The minister said he was commending a pilot study, already under way in the region, which was looking at affordability for those on low incomes and offered special advice on how to cut the bill in each household.

The consumer group Watervoice South West is due to meet MPs and the Water Minister, Elliot Morley, on Wednesday to continue its campaign against the region's soaring bills.