A failure to invest in services for vulnerable children and families could see future costs rise by over nine times their current levels, the Government has been warned.

The business plan of the Child and Family Agency (Tusla), seen by RTÉ's This Week, says there is a "strong and compelling" case for investment.

"Leaving moral and societal values to one side and examining this business case in cold commercial terms, it is clear that resourcing child and family services represents a sensible investment for the State."

The document highlights UK research which estimates savings of over £9 for every £1 invested in early intervention.

The business case notes that such research uses the same methodology as that of Public Expenditure Minister Brendan Howlin's department.

An upfront investment of €79.8m would be needed in 2016 to cover the agency's capital, pay and other requirements, with a further €58m needed by 2018.

An estimated €42.1m would be needed in 2016 to maintain services at current levels.

A failure to invest, the agency argues, will result in discontinuation of services and an inability to respond to the most serious child protection cases in a timely manner.

Preliminary reports of child protection concerns are not all currently being followed up, according to the report, with over one third not being responded to in the initial 24-hour period, as is required.

"Children at serious risk will not be identified quickly and this could result in serious harm to a child", the document warns.

The document expresses concern that resources constraints could also result in the 742 children who have been identified as being at risk not being sufficiently monitored.

It warns of a "failure to monitor child protection plans that ensure children are safe when ongoing risk of harm has been assessed and identified. This can result in significant harm to children and possible death".

Tusla's inability to follow up on over 1,200 retrospective reporting of child abuse made by adults may be leaving children at risk from the same alleged perpetrators and leaving the agency open to legal action.

"Children may be subject to ongoing abuse from an adult perpetrator", the document warns and says that "Tusla may be subject to legal action if our response is not timely and robust in respect of fair procedures".

Tusla also faces additional pay costs of €15m arising from decisions from the Labour Court and Labour Relations Commission.

A Labour Court decision on pay for staff working night shifts will result in an increase of €11m for the agency. Another retrospective pay claim, dating back to before the agency's establishment, will cost Tusla another €4m.

Capital spending of almost €24m is also required, the agency argues, in order to upgrade special care facilities (€20.5m) and roll out ICT (€3.5m) projects, such as the the National Childcare Information System.

Building work includes a fire upgrade at the Ballydowd campus and refurbishment of Creag Aran House for youths with substance abuse issues.

An inability to upgrade facilities would lead the agency to be "guilty of non-compliance on numerous fronts".

These include complying with: "Court orders for the detention of children; HIQA and regulatory standards and fire, Health and safety standards."

The business case also warns of the impact of insufficient investment on staff morale and a danger that board members of the agency may resign.