Two in five households live in fuel poverty, as a result of energy price rises, according to a charity's estimates.
Around 900,000 homes are likely to be spending more than 10% of their income on fuel costs - the official definition of fuel poverty - Energy Action Scotland said.
It based its estimate on the newly published Scottish House Condition Survey by the Scottish Government.
According to the survey, an estimated 684,000 households, 28.9%, were in fuel poverty in October last year, up from 582,000 (24.6%) in July 2011 and up from 658,000 (27.9%) in October 2010.
The rise is caused by energy price rises in autumn last year when some bills were increased by as much as 18%.
Using the survey's figures and adding the effect of further price rises announced in autumn this year, the current number is likely to be around 900,000 households in fuel poverty, Energy Action Scotland said.
The survey also shows that 7.8% of households were in extreme fuel poverty in October last year, spending at least 20% of income on heating and energy.
Energy Action Scotland director Norman Kerr said: "The fact that more Scottish households are now in fuel poverty is very disappointing but not surprising, as energy prices have gone up and people's budgets generally are under pressure.
"Efforts to make homes energy efficient, so that less energy is needed to heat them, are more vital than ever and will clearly have to be increased."
The survey also found that privately rented homes are over three times as likely to have a poor National Home Energy Rating than owner-occupied housing, with 10% of private lets rated as poor compared with 3% of those lived in by the owners.
