CANBERRA (REUTERS) - Australia's opposition, tipped to sweep looming elections, on Wednesday ruled out power-sharing with minor parties and independents in a promise aimed at closing off three years of minority rule that have shaken voters and business confidence.

Opposition Leader Tony Abbott, whose conservatives lead Prime Minister Kevin Rudd's ruling Labor in surveys ahead of the Sept. 7 ballot, said he would not do deals with influential Greens and crossbench independents as the price of taking power.

"This action will protect the economy and jobs. Minority government is an experiment that has comprehensively failed," Mr Abbott said.

Australia's 2010 election delivered the first minority government since World War Two, with centre-left Labor's then leader Julia Gillard becoming prime minister with the support of Green and independent MPs after weeks of dealmaking.

But critics of Ms Gillard's government, including big business and miners, accused the country's first female leader of being unduly influenced by her Green alliance, introducing carbon and mining profits taxes into a slowing economy.

Mr Abbott's pledge to rule out deals in the event of another political deadlock in a country unused to hung parliaments drew a similar pledge from Mr Rudd, who ousted Ms Gillard in June amid plummeting poll support for Labor.

"We will not be entering into any coalition agreements, we won't be having any negotiated agreements," Mr Rudd said.

"Our objective is to be a government, a majority government, in our own right."

Mr Abbott said he had ordered his conservative party leadership to place the Greens behind Labor on ballot sheets, which under Australia's complicated system of preferential voting meant Labor could win some finely balanced seats.

Voting is compulsory for Australians, and the voting system favours the majority centre-left and centre-right blocs by re-allocating votes from failed candidates to more successful candidates.

While less crossbench influence in the lower house would be welcomed by business groups, which have complained about an erosion of stability and investment confidence in Australia in part due to minority government, the Greens will likely remain a force in the upper house.

The Greens hold nine seats in the 76-seat upper house Senate, and only three face re-election, with the rest safe until 2016. Some analysts say considerable voter malaise with the major conservative and Labor blocs could see the leftist party take Senate seats through protest voters.

Greens leader Senator Christine Milne said the move to sideline the Greens was a sign the major parties were worried.

"I say that it's the best message yet to the whole country that if you want effective members of parliament driving progressive change, then vote Green," Ms Milne said.

Mr Abbott's conservatives have made rolling back the carbon and mining taxes the centrepiece of their campaign, along with jobs, economic management and border security to stop a spike in asylum seeker arrivals dividing the country's 14 million voters.

The Labor government this month shaved economic expansion and revenue forecasts ahead of the Sept. 7 poll, tipping growth to slow to 2.5 per cent this fiscal year, down from a previously forecast 2.75 per cent, and joblessness to climb to 6.25 per cent.