The company will reduce sustaining capital expenditure by US$150 million and exploration activity by $10 million.

Guidance for sustaining capex for FY20 was $580 million, while it expected to spend $30 million on greenfields exploration and capitalise $43 million of expenditure.

The company said the reduction in sustaining capex would be realised via a 10% cut this financial year and 18% next financial year.

South32 also said it was working hard to lower unit costs, which would be reflected in FY21 guidance.

The company has suspended the remaining $121 million of its on-market buy-back.

South32 CEO Graham Kerr said the company had already taken steps to ensure the safety of its workforce, but was implementing further measures to protect the balance sheet.

"Our business is well-positioned to successfully navigate this period of uncertainty," he said.

"The initiatives announced today are aimed at delivering approximately $160 million in lower expenditure over the next 15 months to protect our financial position."

South32 had December 31 net cash of $277 million, including cash and cash equivalents of $1.4 billion, no term debt and an undrawn $1.5 billion revolving credit facility.

"The prudent management of our strong balance sheet will continue through our disciplined allocation of capital consistent with our unchanged capital management framework," Kerr said.

"Since demerger, we have returned $2.9 billion to our shareholders by way of ordinary dividends and our capital management program. The disciplined approach we continue to take to capital allocation and our simple capital management framework ensures our shareholders will be rewarded as financial performance improves."

The prefeasibility study for the Hermosa zinc project is still due in the September quarter, but South32 said it was working with Eagle Downs joint venture partner Aquila Resources to preserve the value of the project beyond the investment decision scheduled for the end of the year.

"Sustaining capital expenditure to maintain safe and reliable operations remains a priority, however the flexibility of our programs across the group means that some activity is able to be deferred to future years in response to unexpected market conditions," Kerr said.

"Investing in exploration and our development options to create shareholder value also remains integral to the group's strategy. Our financial priorities remain unchanged, and today's actions, including the suspension of our on-market share buy-back, are a prudent response to the current exceptional circumstances and consistent with our commitment to maintain a strong financial position."

As announced earlier this week, South32 has withdrawn full-year guidance for its South African operations due to the 21-day mandatory lockdown.

The company had been seeking clarification from the government over its operations, and said the Hillside aluminium smelter and domestic production from South Africa Energy Coal continued to operate as they were considered essential.

The manganese operations and export coal production have been suspended.

South32 also suspended guidance for the Cerro Matoso nickel mine in Colombia due to a 19-day lockdown.

The company said none of its other operations had been impacted.

South32 shares were 0.5% higher at A$1.89. The stock hit a 52-week low of $1.585 on Monday.