Yes actually. CSA in Australia can attempt to contact the person in Singapore. However as they don't have actual jurisdiction any legal action is a bit limited. However if you have a court or consent order for Child Support from the Australian Family Court you can use the family court here to issue an order to enforce it I believe. You will need the help of a solicitor.
I not lawyer/teacher/CPA.
You've been arrested? Law Society of Singapore can provide referrals.
You want an International School job? School website or http://www.ISS.edu
Your rugrat needs a School? Avoid for profit schools
You need Tax advice? Ask a CPA
You ran away without doing NS? Shame on you!