Oct 1 (Reuters) - Australian shares were poised to open lower on Monday, with mining stocks likely to weigh on the index after iron ore prices weakened on Friday. Iron ore on the Dalian Commodity Exchange fell 1 percent to 495.50 yuan a tonne on Friday. The Australian energy sector, however, is expected to extend its rally on the back of robust oil prices. The local share price index futures slipped 0.4 percent or 23 points to 6,171, a 36.6-point discount to the underlying S&P/ASX 200 index close. The benchmark gained 0.4 percent on Friday. In New Zealand, the benchmark S&P/NZX 50 index fell 0.2 percent or 16.34 points at 2104 GMT. (Reporting by Shanima A in Bengaluru; Editing by Peter Cooney)