Australia's 70% take hike on ready-to-drink alcoholic beverages, or 'alcopops', hangs in the balance as the country's Senate prepares for a key vote on the issue.

Senators will spend the next few days hearing submissions from health groups, industry and other interested parties on the effects of the tax hike, which was introduced last year.

Australia's House of Representatives last month approved the tax, by a majority of 11, following heated debate. Health minister Nicola Roxon also proposed to extend the tax to include malt and wine-based RTD drinks, such as Diageo's Smirnoff Platinum brand, which was launched in the country in January this year.

US-based drinks group Fortune Brands said in January that the RTD tax rise had been significant in a 16% drop in fourth quarter sales at its spirits arm, Beam Global Spirits & Wine.

Crucial Senate votes on the issue sit with two senators - Steve Fielding, of Family First, and independent Nick Xenophon.

With an opposition coalition set to vote against, the government will require the support of all five Green Party senators and Fielding and Xenophon to get the tax through.

Both Fielding and Xenophon have so far withheld their full backing for the tax, pending talks with government ministers.

The Greens, meanwhile, this week called on the government to establish a special fund for tackling alcohol-related harm, in a sign that a government commitment to this may make or break Green Party support for the tax.

"If government is genuine in dealing with alchool related harm, which is what they say the alcopops tax is about, then they need to be putting their money where their mouth is," said Greens health spokesperson, senator Rachel Siewert.

The government claims the tax rise has been introduced to improve public health and cut young peoples' alcohol consumption. Critics have accused ministers of a disguised "tax grab".