CANBERRA, AAP – Lucrative top-tier mining assets have mostly gone in Australia, so workers need to be flexible to help make new investment possible, mining giants have warned.

BHP, Rio Tinto and Anglo American have told a parliamentary hearing that their way of running a workforce is not about slashing wages, it’s about deploying people differently.

“You only get increased mining employment when you’re able to open and expand new mines,” Minerals Council of Australia spokesman Matthew Steen said on Wednesday.

“We’ve largely explored the easy to mine parts of the continent.”

He said one policy in isolation isn’t enough to shift the dial, but they all have to be moving in the same direction across tax, workplace relations, exploration and infrastructure.

BHP vice president Matthew Furrer said coal is an example of where change can happen quickly, with very low prices through last year.

“For us, it’s critical that we can move our people and resources to where they can be most productive on the day, and that does change,” he said.

Committee member Ben Small, a Liberal senator for Western Australia, said job security is linked to enterprise security.

“No business, no jobs,” Senator Small said.

One Nation senator Malcolm Roberts said workers in some mines were encouraged not to report safety concerns.

Union leaders gave evidence on Tuesday that temporary workers were afraid to raise safety issues, fearing retribution including loss of work.

Mr Furrer said safety, culture and behaviour as well as performance are part of employees’ incentives.

Anglo American is currently reviewing its approach but human resources head Warwick Jones said the company has seen no evidence that paying bonuses to production supervisors increases the safety risk.

As well as global competition for capital, he said each unit of multinational firms must compete internally for funds.

“Our ability to put forward long-term, secure, safe projects is critical,” he said.

The balance of crews across regional mines has tilted towards casuals and contractors over the past decade.

The mining firms say most of their workers are earning well above peers in other industries, and about 1000 apprentices were taken on last year.

Some $26 billion was paid to workers in the Australian resources industry in 2019/20.

“An important part of that is choice – choice about where people ultimately live and locate their families,” Mr Jones said.

“FIFO (Fly In Fly Out), DIDO (Drive in Drive Out) type arrangements that exist are an important part of that choice to allow people some flexibility.”

Mental health providers are concerned these workers also have higher rates of stress, anxiety and depression than the general population.

A Queensland coal mining board inquiry found 50 per cent of workers in the state’s coal sector are on labour hire or subcontracting.

Mr Jones said of the 4600 workers at Anglo American coal operations in Queensland, 1800 are contractors and 480, or 10 per cent, are casuals.