The companies had been in talks a month ago but the plans seemed scuppered when RBPlat's largest shareholder withdrew its support for an Implats deal and sold its circa 33% stake to Northam Platinum.

Yesterday, Implats announced its "firm intention" to make an offer, in cash and shares, after acquiring a 24.52% stake in RBPlat from institutional shareholders.

"The overwhelming response and support of these shareholders is particularly validating of our confidence in the value proposition this offer provides for both RBPlat and Implats shareholders," Implats CEO Nico Muller said.

Implats said it would offer R150 per share to acquire the rest of the company.

The offer comprised R90 in cash and 0.3 Implats share per RBPlat share, implying an 80% premium to RBPlat's 30-day VWAP on October 26, the day before Implats and RBPlat issued their cautionary statements about holding talks.

RBPlat said its board did not have a view or recommendation on Implats' offer "at this stage" but would facilitate it in the interests of shareholders and potential value creation.

CEO Steve Phiri said the company would "continue to engage as appropriate with all bona fide parties in the pursuit of creating value for all our stakeholders".

"Implats' offer and the recent acquisition of RBPlat shares by Northam are testament to the value inherent in this business and to the hard work that our teams have put in," he said.

RBPlat's operations are contiguous to Implats' Impala Rustenburg portfolio in the North West.

The offer is expected to be put to RBPlat shareholders by January 17 and is subject to conditions including regulatory approvals.

Northam has not commented so far on the development.

Implats shares closed up 6% yesterday but are down 11.6% this year, while RBPlat rose 16.5% to take this year's gains to almost 95%.

Implats confirms 3 mud rush fatalities

Separately, Implats said the search for five miners missing since a mud rush incident at its Rustenburg 6 Shaft on November 28 ended yesterday, with two successfully rescued and three bodies recovered.

Two other employees had managed to escape on Sunday with minor injuries.

The mud rush deaths followed a separate fatality during an underground drilling incident at the 16 Shaft on November 27.

Implats said all operations at the 6 and 16 Shaft complexes were suspended until a full and comprehensive report was available.

The deaths occurred within days of a MineSafe conference, which was held to address the worrying rise in mining fatalities in South Africa.