Deloitte Touche won the contract after figures revealed that absent parents owed £690m in CSA-ordered payments to their offspring.

The BBC's Kim Catcheside: "Ministers have decided it's time to get tough"

Less than half of absent fathers had paid the level required by the CSA, while a third had paid nothing at all.

Social Security Minister Baroness Hollis blamed the problem on the complexity of the CSA's assessment process.

She said that about 90% of the CSA's time was committed to assessments which took up to six months per case to complete

That work meant that the CSA did not have enough manpower to collect unpaid debts.

Baroness Hollis said the complexity of the formula also meant that many fathers who did not want to pay could "duck and weave" their way out.

Social Security Minister Baroness Hollis: "We're going to make darn sure they do pay"

Speaking to the BBC's Radio 4 Today programme, Baroness Hollis said that a radical overhaul of the CSA had begun in the government's child support White Paper launched in July.

By the year 2001 the assessments would take six days rather than six months, she predicted.

In the meantime, the consultants would be used as a "stop-gap" to ensure children receive their entitlements.

"We will not let non-resident parents escape the responsibility of looking after their children," she said. "Their children are entitled to this support."

Ian Kelly, of the UK Men's Group, which opposes the CSA, told BBC Radio 5 Live: "I can't really see what a firm of accountants are doing being involved, probably at great expense.

The CSA takes up to six months assessing each case

"There are 50 families in this country who have lost a person by suicide because of the intense pressure that person was placed under by the CSA when they had, in fact, been supporting their child.

"The Child Support Act should be repealed and the matter of child maintenance should be returned to the courts where it was properly dealt with in the past."

'Errors are injustice'

His group was also concerned about increasingly aggressive measures of debt collection, when many CSA assessments have been wrong.

In a recent report, the National Audit Office said the CSA had demanded nearly £24m too much from absent fathers while other absent parents were let off payments worth £6.2m due to errors by CSA staff.

The BBC's Kim Catcheside: "The CSA spends 90% of its time completing complicated assessments"

In all, one in three non-resident parents were paying the wrong amount, and four out of five full-maintenance balances - the running totals of money owed - were wrong.

David Davis, chairman of the Commons Public Accounts Committee, said: "These errors are not notional accounting issues, they represent injustice.

"For every person who gains from an error there is a loser, and where the recipient of child support is on benefit the loser can often be the taxpayer.