An Australian mother who listed her children for sale on the Internet had her joke backfire when authorities were called in to investigate, police said Sunday. Officials in the southern city of Geelong were notified last week that a woman was attempting to sell her children, a boy and girl both aged under 10, on the auction site eBay. Photos of the children were included in the sales pitch. \"Police tracked down the woman, who said it was a joke,\" police said in a statement. Child welfare officers and police conducted a joint investigation and police said no charges would be laid. \"However, police discourage this type of behaviour,\" the statement said.