Here is the ATO link Employee reimbursements and GST http://www.ato.gov.au/print.asp?doc=/content/26349.htm
At the bottom of the first page, it says;
You can claim GST credits if you have relevant documents, such as receipts or tax invoices that were issued to your employee, and if the payments meet the requirements of the GST legislation. Your employee should provide these documents to you to substantiate their claims for reimbursement.
Your employees can not claim the expenses themselves and then claim them from you, effectively claiming them twice. The employee/contractor may record them as an asset account “Reimbursable Expenses Receivable” [though what they do with them is not really your concern].
Refer to : Tax Act substation section of tax act 1997 section 900-1 to 900-250 also FBT Legislation & Tax Ruling 96/7.