Child poverty is linked to the gender pay gap and lack of job opportunities for women, according to previously unpublished statistics released today.

The Fawcett Society said its research showed that two out of five children living in poverty are in single mother households, while a further third have a mother on low or no income.

Lone mothers are at double the risk of being in poverty as couples who have children, said the campaign group.

The report also showed that mothers in the UK were at greater risk of living in poverty than in any other Western country.

Other details included the fact that 30,000 women lost their jobs every year as a result of becoming pregnant, while more women moved into low paid jobs such as cleaning, after they had a child.

The Fawcett Society urged the Government to do more to tackle poverty rates among women by banning the dismissal of pregnant workers, increasing maternity and paternity entitlements, making gender pay audits compulsory and increasing the hours mothers can work without losing their benefits.

Dr Katherine Rake, director of the Fawcett Society, said: "Having a baby in the UK puts women at risk of moving into poverty. This means that child poverty and mothers' poverty have common causes and common solutions.

"We will only succeed in ending child poverty when we address mothers' inequality by ensuring they have access to equal pay, adequate benefits and freedom from discrimination.

"The time has come for the Government to stop keeping mum about the links between women's inequality and children's poverty, and to start taking action to support mums."

Cath Speight, political officer of Unite, which helped with the research, said: "The welfare of children cannot be separated from that of their mothers and it is not acceptable that women and children are living in poverty in this country.

"Women have waited long enough for equal pay - urgent action is now required if the Government is to achieve their target of eradicating child poverty."

Kate Wareing, director for UK Poverty at Oxfam, which was also involved in the research, said: "Child poverty will not be ended if we do not tackle the root causes of why women - particularly mothers - are poorer than men.

"Ending child poverty requires us to raise the income of low-paid women, end discrimination against pregnant women and mothers at work and close the gender pay gap."

Kate Green, director of Child Poverty Action Group, said: "Nearly a third of British children live below the poverty line. Poor pay, lack of flexible working and employer discrimination leave mothers unable to access employment and at higher risk of poverty, whether as part of a couple or a lone parent.

"At the same time, lone mothers with important reasons to stay at home caring for their child are mostly left languishing below the poverty line by an inadequate safety net. Ending inequality for mothers is an important part of ending Britain's child poverty shame."

TUC general secretary Brendan Barber, said: "This report shows how the whole family suffers when women are underpaid and their work is undervalued. The Government cannot hope to meet its commitment of ending child poverty unless serious inroads are made into closing both the full-time and part-time gender pay gaps."

The Fawcett Society said the report was based on official data obtained from the Department for Work and Pensions.