The rules on lone parents' benefits may be changed in a government attempt to get more back into work earlier.
Mr Hutton is worried that lone parents are relying on benefit
Single parents can currently receive Income Support without having to seek work until their youngest child is 16.
But Work Secretary John Hutton told BBC Radio 4 he thought it not "unreasonable" to cut that age to 12.
The Tories said Labour had failed over 10 years to reform welfare. The Lib Dems welcomed the move if the savings were invested in providing childcare.
Charity One Parent Families said it could affect many parents caring for disabled children.
The Office for National Statistics estimates there are 1.69m lone parents with dependent children in the UK.
In a speech, Mr Hutton said Britain has one of the lowest levels of lone parent employment in Europe, with almost half on benefits.
He said up to a third of lone parents move on to incapacity benefit once their child benefit ends as their youngest reaches 16.
Mr Hutton has already unveiled plans to get one million incapacity benefit claimants back into work over the next 10 years, saving £7bn a year.
"If we are to eradicate child poverty, then I believe we will also need to go further in challenging existing assumptions about who - and at what point - someone should be in work," he said.
"We also know the difference that helping lone parents into work can make. A significant proportion of our progress so far in tackling child poverty is due to helping lone parents move into work."
In countries with highly regarded welfare systems such as Sweden and Denmark, up to 80% of lone parents are in work, he said. In Britain, just 56.5% of lone parents are in work.
For the Conservatives, shadow work and pensions secretary, Philip Hammond, said: "Work for parents, both couples and lone parents, must be the key weapon against child poverty.
"Labour have had 10 years to sort out the welfare system and have failed. A last minute rush at the end of Tony Blair's reign is not going to solve the deep problems plaguing the welfare system in this country."
Liberal Democrat work and pensions spokesman David Laws welcomed the plans, but said any money saved must be used to improve childcare.
"It is essential that single parents are supported to stay at home with young children.
"But the fact that British single parents can receive Income Support without any requirement to look for work until their youngest child is 16, is out of line with the rest of Europe."
Labour MP Lynne Jones, who played a prominent role in the backbench rebellion when 47 MPs voted against cuts in lone parent benefits in the late 1990s, warned the plans would "cause conflict" within the Labour party.
She told BBC Radio 4's World at One programme: "It does dismay me that we are still pandering to this stereotype of the lazy, work-shy, lone parent who doesn't do a very good job of bringing up her children anyway."
Clare Tickell, of children's charity NCH, said many parents wanted to work but struggled because of a lack of support.
"Encouraging lone parents to work is a step towards tackling child poverty but they need a package of flexible support to help them juggle the demands of family life and employment," she said.
Chris Pond, chief executive of the charity One Parent Families, said 66% of lone parents with a youngest child aged between 11 and 16 were already in work.
As the government's target was 70%, he said, "this isn't going to take you very far".
A quarter of the parents that would be affected were caring for a disabled child, Mr Pond added.