This represents the first use of electric passenger buses for employee transport in the Canadian mining industry.

In an open letter, investors including Aberdeen Standard Investments, M&G Investments and Legal & General Investment Management said that all lobbying by third parties should be consistent with mining companies’ views and producers should exit lobby groups if this isn’t the case.

The global collapse in coal prices this year has dealt a particularly heavy blow to miners in Indonesia, the top exporter and one of the largest producers of the fuel.

The Carmichael mine has been a lighting rod for climate change concerns in Australia.

Ethical investors have called for the suspension, arguing BHP's membership of some industry organisations funds pro-coal lobbying.

The miner ramped up output at its Illawarra project in New South Wales.