Every fourth single parent household in Sweden lives on less than 60 percent of the median income, which is 188,000 kronor ($26,300) according to Statistics Sweden (SCB) figures for 2008.
"This figures are depressing," said Ulla Andersson of the Left Party, which commissioned the report, to the Dagens Nyheter daily.
The Left Party asked RUT to look at changes in the group classified as poor since 2003, and at regional variations.
The report shows that residents of small industrial towns are worst hit with almost a third of single parents classified as poor, in comparison to less than 10 percent in 2003.
The figures refer to the measure of relative poverty applied across the EU, namely 60 percent of median household income. As average incomes increase so does the threshold for what is classified as poverty regardless of purchasing power or daily calorie intake, which is one of the measures applied by international organisations to measure absolute poverty.
Ulla Andersson argued that the report should be seen as a wake up call and proposes a legal right to child care even after normal working hours, the right to full time work, and an increase in maintenance support and housing allowances, which are currently paid to 260,000 and 120,000 child families respectively.
A broader SCB report published in March, detailing statistics up to 2008, shows that the economic standard for all of Sweden's households has increased dramatically since the turn of the century. This increase confirms however that the gains have not been equally shared by all groups.
The median value of Swedish household income increased by 32 percent from 1999 to 2008, with younger people enjoying greater gains than older, Swedish-born over foreign-born, and men more than women.
While children living with co-habiting parents enjoyed an increase in economic standard of 37 percent over the period, children living with single parents only saw their household incomes improve by 19 percent.
The Swedish government uses the term "low economic standard" to describe the relative poverty line, which currently applies to a disposable income figure of around 10,000 kronor per month.
According to the government budget proposal from October 2009, citing SCB statistics, 12 percent of the Swedish population fell under this classification in 2007, up from 7.5 percent in 1991.
Despite the fact that income differences in Sweden have increased over the past 15 years, Sweden compares favourably internationally, with only Denmark having a more equal division of income among countries included in OECD statistics from the mid-2000s.
The World Bank classifies absolute poverty in global terms as existing on less than $1.25/day (in terms of purchasing power parity) - no one in Sweden currently falls under that category.