* Metals miners, financial firms pull Aussie benchmark lower
* BHP, Rio Tinto (LON:RIO) fall on labour dispute at mammoth copper mine
* But energy companies end at highest in over 3-1/2 years (Updates to close)
Aug 7 (Reuters) - Australia's benchmark share index edged down on Tuesday as BHP and Rio Tinto declined on worries over a labour dispute at a mammoth copper mine in Chile, but energy stocks gained ahead of renewed U.S. sanctions on major oil exporter Iran.
Financial stocks also dragged on the S&P/ASX 200 index .AXJO , which fell 0.3 percent to 6,253.9 in its fourth decline in five sessions. It rose 0.6 percent on Monday.
BHP said on Monday that it had formally requested government mediation with the union at its Escondida copper mine in Chile, where a strike could start as soon as next week if a deal is not reached with workers. Rio is the No.2 shareholder in Escondida, the world's biggest copper mine. in BHP BHP.AX and Rio Tinto RIO.AX fell 1.4 percent and 0.8 percent respectively on Tuesday in the wake of the news.
In the industrials sector, Amcor Ltd AMC.AX , the world's biggest listed packaging company after announcing an all-stock deal worth about $5.25 billion to buy U.S.-listed Bemis Company Inc (NYSE:BMS) BMS.N .
The benchmark's biggest loser, fleet management services provider Eclipx Group ECX.AX , slumped 40.8 percent after trimming its full-year profit outlook. the Reserve Bank of Australia's kept its cash rate at a record low of 1.5 percent on Tuesday. The central bank has notched up two whole years with no move in interest rates as optimism on the economy is tempered by miserly wage growth and muted inflation. financial stocks .AXFJ ended 0.3 percent lower, mainly due to a 1 percent loss in Commonwealth Bank of Australia CBA.AX in the last session before its scheduled annual results.
But the country's energy stocks .AXEJ closed at their highest in over 3-1/2 years, rising in lock step with oil prices in the wake of worries over tighter supply when new U.S. sanctions on Iran are expected to kick in from November. O/R
While all stocks on the sector index rose, Santos Ltd STO.AX racked up the biggest gain.
In New Zealand, the benchmark S&P/NZX 50 index .NZ50 dropped 0.3 percent, with losses in materials and healthcare stocks dragging.
Fletcher Building Ltd FBU.NZ was the biggest influence on the benchmark, ending 2 percent lower.