Premier Mark McGowan says Western Australia’s hard border closures have been vindicated after banking a whopping $5.6 billion, iron ore-fuelled budget surplus.

The state budget predicts a $2.8 billion surplus this financial year to accompany the record 2020-21 outcome, with the finances tipped to remain in the black across the next four years.

Iron ore royalty revenue is expected to peak at an eye-watering $11.3 billion this financial year, despite the price of the steelmaking commodity having plummeted by more than $US100 ($136) per tonne in recent months.

Remarkably, the WA economy has grown 5.7 per cent since the start of the coronavirus pandemic – a figure which suggests WA, based on OECD statistics, would be second only to China as the strongest-growing economy in the world.

Mr McGowan, in his capacity as treasurer, on Thursday delivered little in the way of new promises, having already unveiled major health, housing and infrastructure commitments.

He confirmed the government would fast-track its review of a public sector wage freeze which has capped annual increases for teachers and bureaucrats at $1000 for the past four years.

A decision is expected early next year.

The $5.6 billion surplus last financial year dwarfs the previous WA record of $2.6 billion in 2005-06.

Mr McGowan said it reflected his decision to use border closures to shield the state from major outbreaks while allowing the mining industry to continue operating.

“This budget proves that by putting the health of Western Australians first, by keeping the state safe from COVID-19, we have delivered the best economic and social outcomes in Australia and possibly the world,” he said.

A NSW-style coronavirus outbreak is listed as a major risk to financial assumptions but the budget reveals nothing about when WA will unwind border closures.

Mr McGowan reiterated WA would reopen once between 80 and 90 per cent of West Australians were fully vaccinated.

The premier predicted other state leaders would be “wildly angry” at WA’s economic success, warning he would fiercely resist any bid to unwind the GST revenue deal which guarantees WA a return of 70 cents to the dollar.

Economic growth is expected to slow next year as the iron ore price declines and international borders reopen, driving some consumer activity overseas.

Having avoided any large-scale coronavirus outbreaks, WA has recorded higher business and consumer confidence, building approvals and household spending than any other state.

A building boom, driven by state and federal stimulus, has caused labour shortages which forced the state to push back some infrastructure work.

With health unions blaming a lack of investment for chronic overcrowding and staff shortages at public hospitals, the government has promised to open 332 new beds as part of an additional $1.9 billion health investment.

Other big commitments include an $875 million plan to build 3300 new social homes and a $750 million climate action fund.

A further $1 billion will be allocated to WA’s management of COVID-19, supporting police and other frontline workers.

Opposition Leader Mia Davies said the government had been forced to splash cash on fixing problems of its own making.

“It is extraordinary that we are facing a health crisis of such huge proportions and we have $5.6 billion in the back pocket of the premier. It is a failure,” she said.

The Australian Medical Association said the operational health budget was “grossly inadequate”, with a decline in spending forecast in the outer years.

Industry groups broadly welcomed the surplus but warned the government needed to address labour shortages caused by border closures.