Can I mention that I want to pursue a PhD later, in my Statement of Purpose for a Master's course? I am an international student and a certain university that I'm applying to for a Masters in Media and communication has asked me to state my career objectives in my home country. Now, I wish to pursue a PhD and continue in the same discipline after finishing my masters preferably in the same university. Should I mention that instead? The gist is that I have just finished one masters degree in my home country and have some part-time work experience but my long-term career objective is to pursue a PhD.
Yes, you certainly can mention it. Moreover, this is in many cases, a good sign. When I was on an admissions committee for a masters program, we  in fact looked favorably on people who wanted to do our program and go on to a PhD. This seems to be a common attitude; if students from a program go on to PhD programs that makes our masters program look good.