A Boulder man has been arrested and charged with attempting to sexually engage a child under the age of 13.

Detectives from the WA Police Online Child Exploitation Squad arrested a 27-year-old following a covert police operation.

It is alleged between October and December the man used online facilities to try to engage a police operative posing as a young girl.

He was charged on Tuesday with two counts of electronic communication with intent to procure a child believed to be under 13 to engage in sexual activity.

He has also been charged with one count of using electronic communication with intent to expose a child believed to be under 13 to indecent matter.