Iron ore started November like it ended October, looking to go lower as the price plunged towards $US70 a tonne, the lowest in three years, according to the SGX futures market at the Singapore Stock Exchange.

The price of 62% Fe fines quoted on the SGX market was around $US77 a tonne on Tuesday, after dropping to $US77.17 a tonne on Monday - the final day of August.

That saw the price down close to 18% for the month and close to 24% so far in 2022 and down from $US91.15 a tonne on October 3 (the start of trading for last month).

The fall on Monday (from Friday’s close of $US79.39 a tonne) followed the surprise contraction in Chinese manufacturing and service sector activity last month as President for Life’s Xi Jinping’s zero Covid policy strangled activity at an increasing pace.

China’s official manufacturing purchasing managers' index (PMI) stood at 49.2 from a 50.1 reading in September, the National Bureau of Statistics (NBS) said.

That was supported Tuesday by a similar reading of 49.2 for the manufacturing survey from Caixin group, a private survey which looks mainly at small and medium businesses (while the NBS survey looks at big, mostly state-owned companies).

The 50-point mark separates contraction from growth on a monthly basis and the official survey of service sector activity showed a sharper fall to 48.7, which produced a negative reading on a combined basis of 49 which was must steeper than any forecast has predicted.

Iron ore’s slide was one of the most notable in October as most major commodities fell, though oil rose with Brent futures up 7.8% and US West Texas Intermediate crude rising 8.8% - both solid rises after the weakness in the September quarter.

Comex gold futures fell 1.6% over the month to end at $US1,635.90 an ounce, Comex silver fell 0.6% to $US19.125 an ounce and Comex copper eased 0.8% to $US3.41 a pound and is in danger of easing further as Chinese economic news continues to be dismal.

Meanwhile the Reserve Bank said on Tuesday that its Commodity Price Index rose by 2% in Australian dollar terms last month. Over the past year, the index has increased thanks to "higher LNG, coking coal and thermal coal prices”. The index has increased by 28.9% in Australian dollar terms over the year.

The RBA data suggests the weakness in iron ore prices has lessened its influence in the index’s performance which is still being driven by the fall out in energy markets from the Russian invasion of the Ukraine in late February.