BATON ROUGE, La. (AP) — A state teachers' union has filed a lawsuit challenging the use of Louisiana's public school funding formula to pay $60 million for certain charter schools.

The Louisiana Association of Educators says the spending is illegal because the charter schools are created and operated outside of parish and city school systems. The lawsuit alleges the Louisiana Constitution limits the funding formula to pay for the parish and city systems.

The lawsuit was filed Monday in state district court in Baton Rouge.

At issue are 33 charter schools that are authorized by the state Board of Elementary and Secondary Education and those that could be authorized by local education groups.

Supporters say the schools offer more educational opportunities to students, but public school systems say they siphon dollars away from their schools.