I was fired from my position that I have been employed in for 5 years working on a FIFO basis as a rail technician. My employer is a large well known company. On a routine urine drug test my results were found to be not if normal temperature and maybe had been tampered with. As a result the test was inconclusive and I was tested again with the results showing 2 types of drugs being amphetamine and marijuana. Due to this I was advised to remain of work until my next schedules FIFO Date. Due to a medical issue and family circumstances I was diagnouaed with depression and unfit for work on that date. I remained off work until the next scheduled fly out date with no info or instruction given by my employer of me to do otherwise. I was then contacted my the company whilst on sick leave with medical certificates to prove this that I was required for a meeting with head office with less than 24 hours notice of when I was required and told I could only bring a representative from the company. I did not have a person who could come with me the following day from the company with the short notice and attended by myself. I was in the meeting fired on the grounds of drug results