Mining and metals industry executives ranked access to equity and capital allocation as the most critical risk facing their companies, up from eighth place last year, a survey indicates.

The annual survey "Business Risks Facing Mining and Metals" released Wednesday by consultancy firm Ernst & Young ranks the top 10 strategic business risks in the global sector.

Those risks, the firm says, are being driven by the need to protect returns and manage the interests of varied and often competing stakeholders.

"This is in stark contrast to just 12-18 months ago when fast-tracking production was still top of the agenda and capacity constraints defined the key business risks," said Ernst & Young's Global Mining and Metals Leader Mike Elliott in a release.

The top-ranked capital dilemmas threaten the long-term growth prospects of larger miners at one end of the sector, and the short-term survival of cash-strapped juniors at the other end, the study says.

For larger miners, the rapid decline in commodity prices in 2012, rampant cost inflation and falling returns have created a mismatch between miners' long-term investment horizons and the short-term return horizon of new yield-hungry shareholders in the sector.

Junior miners, the report says, are cash-starved and fighting for survival.

"The dramatic and continuing sell-off in equity markets has starved the junior end of the market of capital," Elliott said. "Advanced juniors and mid-tier producers have been caught in the middle, exposed to a fragile balancing act between investors' thirst for yield and low tolerance of risk".

While Canadian junior explorers were at most risk of going under, he said, the outlook for Australian junior explorers was also grim.

Australian Securities Exchange filings show some small explorers have just thousands of dollars left in the bank, the Australian Broadcasting Corp. reports.

Margin protection and productivity improvement, resource nationalism and the social license to operate followed the top-ranked capital dilemmas in the survey.

The threat of substitutes to mining was a new entry to the survey, ranked as the 10th top concern.

Ernst & Young said the U.S. shale gas boom and the subsequent gas-for-coal substitution occurring in North America has highlighted "the very credible and looming threat of substitution for single commodity companies or companies where one commodity dominates the product mix or profit share."

The threat of substitution has been "transformational" for the U.S. coal market, with global ramifications. "For other commodities, it has the capacity to radically and rapidly change their market should the right conditions prevail," the report states.

Other examples of substitution considered a threat include aluminum for steel, palladium for platinum, graphen for copper and aluminum, plastics, fiber optics for steel.