In what would mark Glencore’s largest takeover bid since its public listing last year, Glencore said it would offer 34 rand ($A4.55) a share through a consortium to take a stake in Optimum.

The move comes after Glencore chief executive Ivan Glasenberg recently said the company would “aggressively” pursue acquisitions and mergers.

If the transaction is approved, Glencore would have access to Optimum’s operations as well as 8 million tonnes of coal export entitlements from Richards Bay coal terminal.

Glencore coal/coke director Tor Peterson said acquiring Optimum’s assets would prove its ability to identify viable opportunities.

“Optimum’s high quality, long life coal assets and significant presence at Richards Bay coal terminal would be an attractive addition to our existing South African coal business,” Peterson said.

“This transaction would further demonstrate Glencore’s ability to identify attractive opportunities, capitalise on its strong local relationships and execute complex transactions.”

However Optimum said the expression of interest it had received from Glencore was not considered “firm” enough.

“The letter does not constitute a firm intention by the consortium to make an offer as contemplated in the Companies Act 71 of 2008,” Optimum said.

“If the board receives a firm offer, it will consider its position and make a recommendation to shareholders, taking into account independent advice received, its own views of the fairness and reasonableness of the proposed offer and any alternative offers.”

Glencore recently launched an 87 cents per share bid to acquire a larger stake in Minara Resources, which would value the nickel company at $1.02 billion.