Liberal Democrat Business Secretary Vince Cable has insisted his proposed "mansion tax" is "very much on the agenda".
He said the tax would ensure rich foreigners with property in Britain contributed to the public finances while creating the "right sort of incentives" for the housing market.
Mr Cable originally proposed the annual levy on properties worth more than £2 million when the Lib Dems were in opposition and it was bitterly opposed by many Tories.
However, Mr Cable told The Sunday Telegraph: "A mansion tax is still very much on the agenda - it is a very good idea.
"It is good for two reasons. It would constitute a tax on wealth rather than income, which we believe to be right, and also in economic terms it creates the right sort of incentives for the property market."
He added it was "perverse" that wealthy foreigners could buy high-value properties in the UK and contribute just £1,000 a year in council tax towards the public finances.