The Joseph Rowntree Foundation (JRF), which campaigns for lasting change for people and places in poverty, has revealed that more than 340,000 households in Scotland fall below the Minimum Income Standard (MIS).
The MIS is set by asking members of the public what they think people need as a minimum in order to have the choices and opportunities to participate fully in society.
Goods and services included by the public are then assigned a price in order to produce figures for how much different households need to earn to achieve a socially acceptable standard of living.
The report found the effects of inflation are being felt most strongly by people on lower incomes as the prices of items most prominent in a basic household budget, such as food and heating costs, have been rising faster than average in the past four years.
For a couple with two children the MIS is currently £685 a week, which includes rent and childcare. For a single person it is £262 a week.
The JRF said there were at least 344,000 households in Scotland that fell below MIS in 2010-11 (the latest year for which figures are available), a rise of 21,000 households since 2008-09. During 2010-11, there were 780,000 individuals living in relative poverty in Scotland, 160,000 of which were pensioners.
The report identified young single adults as the group with the highest increasing risk of living below MIS, due to the growing risk of worklessness in the economic climate and the weak position of younger people in the labour market.
In March, a report into poverty and social exclusion in Scotland found that almost one in 20 Scots were unable to afford an adequate diet, and that one in six children lives in a home that is either damp or not adequately heated.
It also found that 24 per cent of Scottish adults cannot afford one or more basic household appliances, such as a washing machine, a phone, curtains or blinds or table and chairs.
Nick Bailey, of the University of Glasgow, said that the findings painted “a very bleak picture of life” for large numbers of people living in low income households in Scotland today.
He said: “There is little comfort in the fact that levels of deprivation appear to be even worse in the rest of the UK. The absolute numbers in Scotland are still shocking.”
The JRF’s latest findings have prompted Oxfam Scotland to renew its call for a Scottish poverty commissioner.
The charity said the rise in the number of homes below MIS shows the urgent need to place policies that tackle poverty at the heart of government, and said a poverty commissioner would ensure that happens.
Judith Robertson, head of Oxfam Scotland, said: “The poorest people in Scotland are facing a perfect storm of rising living costs, falling incomes and government cuts. They are struggling and the gap between them and the richest people has grown massively over the years.
“Change comes through consistent pressure. We believe a poverty commissioner for Scotland would ensure that this issue was always high on the agenda of our politicians.”