The Scottish Parliament's education committee, which is embarking on an early years inquiry in September, has already received a number of written submissions about the knock-on effect of last year's industrial dispute.
The Scottish Pre-School Play Association has also warned that, despite the voluntary sector receiving substantial funding to cover its partnerships with local authorities, this money only covers 33 weeks of two and a half hours a day, five days a week.
"Most voluntary sector groups operate for at least 38 weeks a year and staff are on the premises more than two and a half hours per day as they have to prepare, plan and carry out child assessments," the SPPA states.
It adds: "The dilemma for the groups has been how they fund the missing five weeks. If a group charges fees, they have the possibility of losing business to the neighbouring local authority nursery where this unfunded period can be funded from a council budget."
As a consequence, a number of voluntary pre-school playgroup providers have closed down or opted out of the regulatory framework, decreasing the number of pre-school places available in the sector from 45,883 in 1997 to 20,061 in 2003.
In its submission to the inquiry, the Convention of Scottish Local Authorities, states: "Since rates of pay were increased, and due to the considerably better holidays and other terms and conditions highlighted during the dispute, it is becoming increasingly difficult for other providers to recruit and retain staff."
The charity CARE (Christian Action Research and Education) warns that the local authority pay awards are "generally beyond the ability of private providers to pay".
It adds: "We feel strongly that the wider choice available to parents through private providers should not be allowed to wither because of the greater financial resources of local councils."
Lord James Douglas-Hamilton, deputy convener of the education committee, said: "We know how important the early years are in helping each child reach his or her potential which is why the committee wants to examine the progress made by the Scottish Executive in delivering effective childcare and education for pre-school children.
"We will be looking at progress in improving the availability and flexibility of childcare and the kinds of choices open to parents - especially in low-income areas."