Voluntary and community playgroups claim schools are getting up to four times more cash than they are to pilot Wales's new play-based curriculum for three to seven-year-olds.
The Wales Pre-School Playgroup Association (WPPA) says it will make it more difficult for its hard-pressed volunteers - who work with more than 29,000 under-fives in Wales - to get to grips with the new foundation phase.
But an Assembly spokeswoman said playgroups were getting less cash because they are already better staffed than school reception classes.
The funding differences emerged as a draft learning framework setting out the new foundation curriculum was published this week. Children as young as three will be taught to respect the values of other cultures but formal lessons, in subjects like maths and English, will not start until age seven. However, older children will still have to tackle phonics, grammar and arithmetic, and English-medium schools and playgroups are expected to promote Welsh.
Children's personal development and well-being are at the heart of the new foundation phase, with learning taking place mainly via structured indoor and outdoor play activities. The framework drops the subject-based focus of the key stage 1 curriculum in favour of seven "learning areas" - a format more familiar to nurseries and pre-school playgroups than KS1 teachers.
From September, 41 schools and playgroups will be piloting the foundation phase with three and four-year-olds, and the pilots will be extended to Year 1 and 2 pupils in 2005 and 2006.
But the WPPA, which represents 12 of the 19 pre-school pilots, says its members - and children - are losing out. It claims they will receive pound;500 for training staff and observing good practice elsewhere, compared to pound;2,000 for schools; and only pound;300 for learning resources, compared to pound;1,000 for schools.
Thomas Memery, the WPPA's director, said: "One of the explanations given is that schools do not have the play equipment and playgroups do. We don't accept that. We are talking about community groups with honesty boxes and volunteers. There's a lot of goodwill but they lack money."
An Assembly spokeswoman said funding for the pilots had yet to be finalised. But playgroups are not expected to require funding for extra staff because they already have one adult for every eight children, whereas pilot schools may require more teaching assistants.
Despite funding concerns, the WPPA and other organisations are strongly in favour of the foundation phase. Research has suggested that having formal lessons too young can damage learning.
Gethin Lewis, National Union of Teachers Cymru general secretary, said: "We fully support the philosophy behind the foundation phase. What we do not want to see is this exciting prospect being undermined by a lack of funding."
Jane Davidson, education and lifelong learning minister, said: "A strong focus on all-round growth and development will give children the best start in life and in particular support those facing disadvantage and poverty."
Subject to the pilots, it will be 2008 before the new framework is introduced nationally. But parents remain to be convinced about learning through play. Told that formal lessons would not begin until age seven, 58 per cent of 300 parents surveyed by TES Cymru earlier this year were opposed.