Conscientious objection to childhood immunisation is on the rise as parents exploit a loophole in the new ''no jab, no play'' law that allows unvaccinated children to be enrolled in childcare centres.

The federal Health Department says 3910 parents across Australia lodged a conscientious objection form last year, the highest number recorded by the Australian Childhood Immunisation Register since 1999.

Worried about infection: Fenella Cios, director of Fenella's Family Daycare, with Ellie Graf, 2, nine-week-old son Oliver and Victoria Dale, 18 months. Credit:Tamara Dean

It takes the total number of conscientious objectors to 36,320, out of more than 2.2 million children on the register.

The highest number of objections came from NSW parents, who accounted for 9625 of the total number of conscientious objectors at the end of last year. That was 1102 more than at the end of 2012.