Prices of iron ore, the nation’s biggest export, continue to defy expectations as Chinese steel demand and prices hit new highs, leading to predictions of sustained iron ore price strength and the potential for extra cash to flow to government coffers and the pockets of Australian mining investors.

As analysts boost 2017 iron ore price expectations, all eyes will be on BHP Billiton and Fortescue Metals Group when they report earnings this week, to see whether they are confident enough to boost dividends.

Benchmark prices of the steelmaking ingredient held above $US90 a tonne on Friday night as traders began buying after a lull last week in the wake of increased production by Brazil’s Vale.

The price rose US31c to $US90.37 and looks set to test a two-year high of $US91.80 hit a week ago.

While many pundits have pointed to volatility in the spot market as a reason not to get too excited by price spikes, analysts say Chinese steel prices are at four-year highs for solid fundamental reasons and that there is plenty of evidence of strong demand for iron ore.

UBS analyst Lachlan Shaw said iron ore prices had been much stronger than the bank had expected.

“Even with record high (Chinese port) stocks, most other signals remain supportive in the short term and seasonally strong demand in the second quarter beckons,” Mr Shaw said.

He said the company’s average 2017 forecast of $US56 a tonne was looking like it could be upgraded to $US66.

Chinese iron ore demand typically picks up in spring as construction activity increases after the Chinese New Year.

This is expected to provide an extra boost at a time when demand has been strong because of Chinese stimulus packages.

Iron ore prices at Australian ports have averaged about $US64 a tonne before shipping since the start of 2016-17, up substantially on a $US55 a tonne budget forecast that was viewed as optimistic when it was delivered in May last year.

If prices can stay around current levels, it could result in an extra $3 billion of company tax revenue for the federal government in 2016-17.

According to Bloomberg estimates, analysts expect BHP to report underlying first-half profit of $US3.4bn after the market closes tomorrow, a more than eightfold rise on a year earlier on the back of rising commodity prices.

Deutsche Bank expects the miner, which last year abandoned its progressive dividend, to focus on paying down debt and announce a US28c per share dividend. But there a wide range of expectations, with RBC forecasting a US14c return and Credit Suisse flagging a US41.1c payout.

Fortescue, which reports on Wednesday, is forecast to deliver a $US1.22bn underlying first-half profit, up from $US319m a year earlier.

“Fortescue is arguably the best-placed for a dividend surprise, having largely achieved its debt-reduction plans,” said RBC analyst Paul Hissey, who is expecting a full-year dividend of US25c per share.

Credit Suisse is predicting Fortescue will pay a US16.8c interim dividend.

Credit Suisse analyst Matthew Hope said talk of record iron ore stockpiles at Chinese ports would not necessarily weigh on prices.

He said a Mysteel survey of steel mill holdings, which include stockpiles at the mills and at the ports, was not showing high levels, indicating steel yard inventories were weak.

He noted that last time steel prices were this high, four years ago, iron ore prices were $US155 a tonne.