Available jobs in Australia shrunk a bit in May amidst the uncertainties still faced by many companies as more job opportunities could further disappear should the mining industry continue its plans to cancel lined up projects in light of the planned resource rent tax by the federal government.

Figures furnished by IPA recruitment agency on Thursday revealed that job vacancies plunged by four percent in May as against to the 20.9 percent increase seen in March, which IPA chief executive Rabieh Krayem attributed to cautious employers notwithstanding the economic gains being experienced lately.

He said that employers are indeed aware that Australia's economic recovery is underway but are wary at the same time that much of the world still struggles and "most employers still bear scars from the GFC (global financial crisis) and will not risk over-burdening themselves."

Mr Krayem added that most companies looking to expand are encountering problems in securing credit from the banks, which resulted to tentative hiring from companies as he cited that "in April we had more hiring than in March as employers were making smaller orders."

Adding more woes is the impending resource tax from the federal government that could further decimate the available jobs once mining projects are either cancelled or put on hold.

Mr Krayem noted that mining has provided the engine rooms for job creation in Australia in recent times, and he is projecting that "if projects are shelved because of the decision then the impact on employment would be significant."

As spurred by the recent Henry tax review, the federal government is poised to implement the new super tax that will require resource companies to pay 40 percent of profits made from exploiting Australia's non-renewable resources.