Hi Jane,

At our company confidentiality is a very serious matter and talking about employees salaries will not be tolerated. It will be immediate dismissal, but it is stipulated in our contracts as such. I would suggest that you have a look at the contract she signed and see what it says (you cant dismiss her if it does not say so in the contract)

If you can not dismiss her I would say it is serious enough for first written warning and a serious talk - salaries are such a sensitive thing (that one gets more than me, but does less blah blah blah)