The number of lone parents is rising by a rate of more than 20,000 a year with "devastating" consequences for children and adults alike, warns the Centre for Social Justice.

In a report, the CSJ says the number of lone parents will pass two million by the time of the next election.

The increase is not being fuelled by divorce but by the surge in cohabitation, the report states. Since 1996, the number of people cohabiting has doubled to nearly six million but cohabiting parents are three times more likely than married couples to separate by the time a child is five, the report states.

The number of lone parents increase by almost a quarter between 1996 and 2012 to just under two million adults, mostly women.

Britain has one of the highest rates of family breakdown in the developed world, with a quarter of families with dependent children being headed by a lone parent.

Around a million children are growing up without any contact with their father and some of the poorest parts of the country have become "men deserts" because there are so few male primary school teachers. Across England and Wales, one in four primary schools has no male teacher and 80 per cent have fewer than three, the report says.

CSJ director Christian Guy said: "For children growing up in some of the poorest parts of the country, men are rarely encountered in the home or in the classroom. This is an ignored form of deprivation that can have profoundly damaging consequences on social and mental development.

"There are 'men deserts' in many parts of our towns and cities and we urgently need to wake up to what is going wrong."

The area with most lone parents is Manor Castle in Sheffield, where among the households with dependent children, 75 per cent are headed by a lone parent, most commonly a woman.

This is followed by the Riverside neighbourhood in Liverpool, where 71 per cent of households with dependent children are headed by a lone parent. Five Liverpool neighbourhoods are in the top 20 nationally for lone parent households.

According to the report, there are 236 LSOAs (lower layer super output areas) in England and Wales where more than half of households with dependent children are headed by a lone mother.

The report warns that the absence of fathers is linked to higher rates of teenage crime, pregnancy and disadvantage.

It is also costly. The CSJ puts the total cost of family breakdown at £46 billion a year, or £1,541 per taxpayer, a figure which has risen by nearly a quarter in the last four years. On current trends, the cost of family breakdown is projected to hit £49 billion by the end of this Parliament.

The CSJ criticises the lack of Government investment in families, saying that for every £6,000 spent on picking up the pieces after a split, just £1 is spent on helping to keep families together.

The report accuses the Prime Minister of neglecting his election pledge to lead the "most family-friendly Government ever".

The family stability agenda "has barely been mentioned", the CSJ says, while comprehensive action to tackle existing policy barriers to family stability "has been almost entirely absent".

Guy called for a change to the political discourse on family breakdown.

"There are many misguided reasons for such political paralysis. Some argue that it is no business of politicians to meddle in the personal family choices people make. Others suggest that rising family breakdown is just a modern process, an inevitable trait of human advancement. Others say family instability doesn't matter.

"This has to change. Our political discourse about family policy must mature. Family breakdown is an urgent public health issue. Backing commitment and setting a goal of reducing instability does not equate to criticising or stigmatising lone parents or those involved.

"Within this need for new maturity, we should also agree that marriage is not a right wing obsession but a social justice issue: people throughout society want to marry but the cultural and financial barriers faced by those in the poorest communities thwart their aspirations," he said.