Australia's parliament voted overwhelmingly on Thursday to defeat a motion aimed at sinking China's proposed $19.5 billion investment in Anglo-Australian miner Rio Tinto (RIO.AX: Quote) (RIO.L: Quote).

The Greens party, which opposes the investment by state-owned aluminium group Chinalco, had asked the upper house Senate to call upon Treasurer Wayne Swan to deny foreign-investment approval for the deal, unless he imposed a virtually impossible condition.

The motion by Greens leader Bob Brown called for Swan to obtain assurances that the Chinese government could not appoint or remove any executives of Chinalco.

Brown believes Beijing could use Chinalco's influence for its own ends.

We are marking 50 years of domination of Tibet, and there needs to be absolute assurance that the people who can put Tibet ruthlessly under subjugation are not able to determine what happens to our resources in Australia, Brown told Reuters.

We are talking about a police state, not a democracy, and a ruthless authoritarian government in Beijing.

The motion was backed by only the five Greens senators and did not even spark a debate, after government and conservative opposition senators opposed the move.

Chinalco plans to pay $12.3 billion for stakes in key iron ore, copper and aluminium assets from debt-laden Rio and $7.2 billion for convertible notes which double its equity interest in the company to 18 percent.

Australia's Foreign Investment Review Board is reviewing the Rio-Chinalco deal, but Swan must make a final decision on whether the deal is in Australia's national interest and whether the deal should be approved, vetoed or approved with conditions. (Reporting by James Grubel, Editing by Mark Bendeich)

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