Owners of empty homes should be hit with council tax bills worth 500% of current levels, Liberal Democrat leader Sir Vince Cable has proposed.
The former Coalition minister has called for radical change to fix the housing crisis blighting Britain.
In a major speech on housing, Cable has also demanded loans of up to £2,000 to help people without cash in the bank to pay the deposit on a rental property.
He called for a stamp duty surcharge for overseas residents who want to buy property in the UK.
Research by the Liberal Democrats earlier this year found 11,000 homes across the country had been lying empty for more than a decade.
Some 60,000 had not been occupied for two years, while 23,000 had been left for five years or more.
Under current rules, councils can charge the owners of empty properties double the council tax rate – but Cable said it should be 500%.
“There is little recognition that radical change will be necessary if the crisis in housing is to be properly addressed in our lifetime,” the ex-business secretary said in central London.
“As we build more homes, millions will continue to live in the existing stock of social housing, privately rented property, and owner-occupied property, many of them faced with poor conditions, unaffordable rents and instability.”
He added: “We need an end to exploitative, greedy, negligent or neglectful practices in the private sector, which gives the majority of good landlords a bad name.
The average tenancy deposit in England and Wales is more than £1,000 according to the Tenancy Deposit Scheme, while in London the sum is £1,750.