Notice Period in Australia - working on deputation for a major Indian IT company

I am a software engineer recently moved from India to Aus. I have a PR and am currently working on deputation for a major Indian IT company. My work duration is 9 weeks in Australia. I am unhappy with this but the company has refused to extend it. Its been just two weeks here and I already have got a decent offer from an Aus company. My team mates are confusing me saying I need to provide 12 weeks of notice as is the norm in India. I am yet to speak to HR but the moment I go to HR, my manager will get to know and may try to get my resignation delayed/rejected.. I am confused. I saw in NES website that the notice period is 4 weeks if I have served more than 5 yrs in the company (I have worked for the same company for 9 yrs in India). What will be my notice period? Can anyone advice?

Your company indian based...So all indian labour laws applicable as per. Your contract norms.
Leaving the job abruptly sends signal as unreliable employee..
So try to complete your training period successfully and go for resignation as per your contract.... If there is 3 months ask for your company for a remidy of relieve by paying some cash penalty usually it is there in every company...
Going for another best choice is quite common now a days....Try to Avoid negative approach with management ..Convince with your communication talents...All the best sir.

You have to follow your company policies that were mentioned in your offer letter. You can go for Notice pay so that you can get the experience letter from HR.
Meanwhile you try to request some duration to your new company or ask them if they are ok with no experience letter, if your current employer doesn't accept resignation.

Iam in same situation.Do you mind sharing what happened with you ?

In many cases here in Oz, notice period is often in line with how you are paid, ie paid fortnightly, it's 2 weeks notice, paid monthly, it's a month's notice. But individual company's may have different policies.

The company may be Indian based, but they are not exempt from following Australian labour laws if they have a branch here. But I have very little knowledge of labour laws, and have been retired for 8 years. Much has changed over the years.

We don't have such a thing as experience letters here. Seems to be a peculiarly Indian thing I suspect.