An internal investigation has led to charges against a Canada Post employee who is accused of opening mail that didn’t belong to her and stealing the contents inside.

Toronto police say the employee was put under surveillance by Canada Post last month and allegedly was seen stealing mail that contained gift cards.

"They set up an operation," Const. Tony Vella told CBC News on Tuesday.

"It’s alleged that she opened up mail that didn’t belong to her and that items were taken from the mail."

The employee was arrested and subsequently charged by police.

A 64-year-old Toronto woman faces five criminal counts, including criminal breach of trust, theft from mail, possession of property obtained by crime and two counts of opening mail unlawfully.

Both Canada Post and Toronto police are advising the public not to send cash through the mail.