Australia's school chaplaincy program faces a constitutional challenge in the High Court as opposition grows to having government funding paying for God's representatives in state schools.

Labor and the Coalition have said they will make $220 million available over four years to fund 1000 more chaplains, but the Australian Psychological Society has said the program is dangerous to children's mental health.

Under the federally funded program, schools can apply for up to $20,000 a year to support or initiate chaplaincy.

The Australian Council of State School Organisations calls chaplaincy ''the wrong response and for the wrong reasons''.

Chaplaincy organisations say parents and principals welcome chaplains, seeing them as a valuable adjunct to other welfare services.