The iron ore price pushed higher overnight and is continuing to hover around three-month highs, defying two fresh calls for a looming slump.

Iron ore rose 0.8 per cent to $US61.60 overnight, according to The Steel Index, from $US61.10 in the previous session.

The commodity is now a whisker below the three-and-a-half-month peak of $US61.80 it reached last week, buoying large and small producers despite expectations the rally will not last.

The price’s strong showing boosted Australia’s mining giants in London trade and could flow through to the local market today. BHP Billiton shares jumped 4.4 per cent in London, while Rio Tinto rose 2.7 per cent.

Ratings agency Moody’s last night upgraded its credit ratings for pure play iron ore producer Fortescue Metals Group, following the miner’s aggressive debt repayments on the back of cost cutting and the surprise price rebound that helped it triple its full-year profit this week.

But Moody’s warned that iron ore prices are likely to stay volatile and could fall further, with its base case for the steelmaking ingredient set at around $US45 a tonne. Fortescue’s lower costs and debt should help it better manage this volatility, Moody’s said.

Elsewhere, analysts at Citi called the Fortescue profit a “great result”, but reaffirmed a sell call on the miner due to the bank’s bearish outlook for iron ore.

Citi affirmed its forecasts of an average iron ore price of $US42 a tonne in 2017 and $US38 a tonne in 2018, which are towards the more negative end of the spectrum of expectations.

Meanwhile, iron ore futures in Dalian rose to their highest level in two years, as Chinese steel mills restocked their supplies of the steelmaking commodity.