Scotland has increasing numbers of people who are living below the breadline, according to a survey which shows the north-south divide on poverty in Britain is getting wider.

The Joseph Rowntree Foundation, the social policy research charity, says the UK has become a segregated society with the gap between rich and poor reaching its highest level for more than 40 years.

Poverty levels are based on various social conditions including unemployment, lack of owner-occupied accommodation, lack of car ownership, limiting long-term illness, lone parent households, and low social class.

The research, carried out for the foundation by academics from a group of UK universities, shows that in 2000, for the first time, there were areas of southern Scotland where there were 30% to 40% of the population breadline poor.

Typically the rest of Scotland had breadline levels of 20% to 30%, which was largely the picture in 1970.

Meanwhile, the vast majority of the UK retained breadline poverty rates of around 10% to 20% between 1970 and 2000.

The report shows that UK-wide in the past 15 years there has been an increase in the number of households living below the poverty line, with these households accounting for more than half of all families in areas of some cities. Researchers working on the report, which compared poverty surveys over the past four decades with housing equity data to analyse the ever-changing face of wealth distribution, found that households in already-wealthy areas have tended to become disproportionately wealthier and that many rich people live in areas segregated from the rest of society.

The widening gap between rich and poor led to a fall in the number of average households, which were classed as being neither rich nor poor, with these families gradually disappearing from London and the South East, the report said.

Since 1970 levels of poverty and wealth in different areas of Britain have changed significantly, with the country now moving back towards levels of inequality last seen more than 40 years ago.

While the number of people who are living in extreme poverty has fallen, the number of people living below the poverty line has increased, with more than one in four households in Britain classed as being so-called breadline poor in 2001.

At the same time the number of asset-wealthy households rose dramatically between 1999 and 2003 with more than one-fifth of families now falling into this category.

However, the proportion of average households fell from around two-thirds of families in 1980 to just over half by 2000.

Danny Dorling, professor of human geography at Sheffield University, one of those who headed the study said: "My own view is a global recession would stem the tide of the widening gap between rich and poor - although that wouldn't be good for anyone."