A sergeant with the WA Police force has been charged with child sex offences after allegedly sending a boy material of a "sexual nature".

Police have alleged the sergeant sent the boy "inappropriate images".

The officer works in the Perth metropolitan area.

"He has been stood down from duty," a police spokesman said.

The sergeant has been charged with using electronic communications with intent to expose a person aged under 13 years to an indecent matter.

He has also been charged with encouraging a child to perform an indecent act.

The man will appear before the Mandurah Magistrates Court tomorrow.