The number of children attending pre-school nursery education fell by 6% last year, figures have revealed.
All three and four-year-olds are entitled to a free nursery place
The Scottish Executive said it was puzzled by the drop, which showed 6,700 fewer three and four-year-olds taking up the free nursery place provision.
The executive's own annual census said that 81% of three-year-olds and 97.8% of four-year-olds were now registered.
The Scottish National Party said that the short nursery hours offered under the scheme caused problems for parents.
Under the scheme all children aged three and four are eligible for a free part-time pre-school place.
The pattern differs slightly for each local authority but a child is usually offered five sessions of education a week, of about two-and-a-half hours each, throughout the school year.
The Pre-School and Childcare Statistics 2005 showed that there were as many as 96,460 children attending pre-school education in Scotland in January 2005.
A year previously 85% of three-year-olds were registered with pre-school education centres.
This had fallen by 4.4 percentage points in 2005.
The percentage of four-year-olds registered fell by 2.2 points from 100 to 97.8%.
A Scottish Executive spokeswoman said that, overall, the number of children in pre-school education was "healthy".
"Uptake for four-year-olds remains close to 100% and for three-year-olds is still over 80%," she said.
"Nursery education is optional and it's for parents to decide what's best for their children.
"However, we would encourage parents to make the most of free provision."
SNP education and young people spokeswoman Fiona Hyslop said that the current statutory provision was less than 11 hours per week.
She said: "The SNP wants to increase this to a full half day as one of the first steps on the road to a comprehensive package of childcare and early years learning measures."
Intend to leave
The statistics also showed that there were 6,100 childminders in Scotland in January 2005.
This is a slight decrease from 6,165 in 2004.
Childminders are most common in least deprived areas.
Almost 18% of childminders had already left or intend to leave childminding in the next year.
The median charges of childminders are £3 per hour, £21 per day or £88 per week.