More than one third of British consumers believe that Labour’s proposals for a mansion tax on homes worth more than £2 million ($A3.65 million) would be unfair while more than half would be supportive of the measure, according to a survey by a property website.

Rightmove, which carried out the research, also estimates that fewer than one in every 100 properties currently on the market would be affected by the proposed levy.

Its survey of 2700 people carried out last week found that 38 per cent of people believe that a mansion tax would be unfair.

But more than half (52 per cent) of those surveyed think that it would be fair to introduce such a tax.

The remaining 10 per cent were not sure either way.

Rightmove’s analysis of its own website found that less than 1 per cent of properties for sale have a price tag of more than £2 million.

Nearly three-quarters (72 per cent) of these properties are in London, while one in six (16 per cent) are in the South East.

Labour’s mansion tax plans were unveiled last week and would have the objective of boosting funding for the NHS.

They have been criticised by estate agents as being effectively a tax on people living in southern England, which already bears the brunt of stamp duty charges due to higher house prices there.