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.

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.

Under the ''no jab, no play'' law, the documents must be signed by a GP or medical practitioner. Doctors can only do so after explaining to parents the benefits and risks of immunising their children against vaccine-preventable diseases.

Childcare centre operators face fines of up to $4000 if they do not keep immunisation records up to date.