if she is good looking count your lucky stars and go for it.We dont all get this chance.But maybe dream of it,on the other hand if you are in relationship and not bothered then as above,be polite and state its a proffessional or working relationship and thats it.
Ask HR - your firm should have a written policy on sexual harassment (which I think this is) and what to do about it, you should follow the procedure to the letter. Nip it in the bud before it's construed that by your silence you consented. And before other people have the same experience, or yours is escalated to something more serious. Keep a diary of what was done to you and how you felt. Personally, having had this experience myself, I would say firmly "What you are doing is not appropriate, and if you touch me again, I will lodge an official complaint with my line manager." Girl-on-girl (or boy-on-boy) is especially difficult to deal with as it's more of a taboo topic at work. But when I was groped from behind by a senior lawyer (i.e. no-one above him to complain to, my own boss just laughed), I put a notice up in the Ladies to warn others - turned out that most of the women had benefitted from his attentions. We turned him into a joke and made sure we were never alone with him.
When I was in the workplace, I encountered a few women who were "touchers" and I tolerated it, but didn't feel too comfortable about it. I wouldn't say anything or complain, but on one occasion, I was grabbed quite intimately from behind and it made me realise how women must feel when they are subjected to the unwanted attentions of men. I have found that the best way to stop it happening is to become old and unattractive.
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