South African miner Tharisa on Wednesday deepened its exposure to Zimbabwe, saying it had bought a 26.8 percent stake in platinum group reserves for $4.5 million and could increase its presence greatly if conditions are right.

Tharisa has made clear its interest in moving into Zimbabwe's Great Dyke region, which is considered to have chrome and platinum reserves comparable to those it mines in the Bushveld region of South Africa.

In May it bought a 90 percent stake in a Zimbabwean chrome.

It has added to that with a deal that gives it access to an area covering 23,903 hectares on the Great Dyke of Zimbabwe, containing an estimated 96 million ounces in platinum group metals, including platinum and palladium.

Both assets have been acquired from holding companies owned by the Pouroulis family that leads Tharisa.

The family's Cyprus-based Karo Resources signed a $4.2 billion outline deal in March to develop a platinum mine and refinery in Zimbabwe, although it was not clear when the full investment would be made.

Tharisa CEO Phoevos Pouroulis on Wednesday told Reuters Tharisa would adopt a phased approach and could increase its exposure further.

"It's a once in a lifetime opportunity," he said, adding the company was getting early mover advantage as Zimbabwe opens up to international investment.

Zimbabwe in July is set to hold its first election since Robert Mugabe's downfall in November after nearly 40 years in power.

Analysts say many in the mining community excited by the country's mineral wealth are waiting for the results of that vote before making decisive moves.

Tharisa says the platinum group reserves it is acquiring are a tier one resource, a term used in mining to refer to assets that are large enough to be mined over decades, although the extent of them still has to be formally proven.

They are richer in palladium than platinum, a metal that has outstripped platinum in value as the market for diesel vehicles -- a prime use for platinum -- has been hit by concerns about pollution.

Karo Holdings' deal with Zimbabwe in March over time aim to establish a mine, treatment plants and power generation.

Tharisa is taking a step by step approach and so far has bought into the project at a discount, analysts said.

Peel Hunt in a note said the "modular approach" was wise.

"Importantly these come on a case-by-case basis, not all-or-nothing," it said.