Sept 25 (Reuters) - Australian shares were poised to open steady on Tuesday, as gains in the energy stocks on the back of firm oil prices are likely to offset weakness in the mining sector. Global benchmark Brent crude jumped on Monday to a four-year high above $80 per barrel after Saudi Arabia and Russia ruled out any immediate increase in production. The local share price index futures fell marginally to 0.1 percent or 6 points to 6,182, a 4.9-point discount to the underlying S&P/ASX 200 index close. The benchmark fell 0.1 percent on Monday. New Zealand's benchmark S&P/NZX 50 index dipped 0.2 percent at 2207 GMT. (Reporting by Shanima A in Bengaluru; Editing by Lisa Shumaker)