They are holding a press conference on Thursday to highlight their concerns and say research shows that one in four women has experienced domestic violence.

The government is due to publish its White Paper on reform of the Child Support Act shortly.

Its 1998 Green Paper, Children First, puts forward several proposals for simplifying the system by which absent parents pay maintenance for their children.

They include plans to give parents more incentives to co-operate with the Child Suppport Agency (CSA).

More than 70% of lone parents on Income Support do not get any extra money for their children if maintenance is paid.

Many do not co-operate with the CSA.

The government claims this means the taxpayer is forced to provide support for more than 1.8 million children because their absent parents are not paying maintenance.

'Drastic effects'

But the Single Mothers' Self-Defence group, a network of mothers in the London and Manchester area, says many of these may have been victims of domestic violence.

It says its views are supported by more than 100 women's organisations in the UK.

Kim Sparrow, a spokeswoman for the group, said: "We want to publicise the drastic effects the proposals will have on single mothers and children's safety.

"The reforms are trying to make it easier for fathers to have access as a pay-off for coming up with money.

"But 75% of single mothers on Income Support are refusing to co-operate with the CSA. This is a massive refusal.

The CSA has been at the centre of controversy since it was set up in 1993

"Instead of looking at why they are refusing and putting it together with the high levels of domestic violence, they say it is fraud and that mothers have private arrangements with the fathers."

The self-defence group says co-operating with the CSA should be a mother's choice and they should not be threatened with benefit cuts if they decide not to.

Currently mothers can lose up to £20 a week of their benefits if they do not co-operate with the CSA.

The self-defence group, which started up in 1987 and has campaigned on a variety of issues including proposals to cut single parent benefits, says it believes the government is likely to tighten the wording which allows women not to co-operate with the CSA.

It now says that women who can plead a special case that they would suffer "harm or undue distress" if they were in contact with their former partner.

The self-defence group says this could mean more would suffer benefit cuts if they could not prove domestic violence.

Ms Sparrow says many women do not report domestic violence until they have been assaulted a number of times.

Saving money

She added: "Single parents should be entitled to benefits for the work they do raising children.

"The CSA has always been about saving the government money and not about supporting women."

A spokeswoman for the Department of Social Security said the self-defence group's concerns, which have been submitted to the government, would have been considered in the preparation of the White Paper.

The government believes its plans for the CSA will help both parents by simplifying the system.

And its says a proposal that single parents on benefits will be able to have £10 a week of benefits disregarded if they receive maintenance will encourage them to co-operate with the CSA.

One of the main aims of the reforms is to encourage both parents to play a role in raising their children.