LONDON, June 28 (Reuters) - Platinum miner Lonmin Plc came to the aid of its financially stretched African cousin, Ashanti Goldfields Co Ltd , on Friday, pumping $75 million into the firm to protect its minority shareholding

Lonmin, which had previously baulked at injecting more money into Ghana-based Ashanti, was prompted by a recent surge in the gold price to make its 11th hour offer -- after the gold miner had already agreed a life-saving debt overhaul with its lenders.

Lonmin, the world's third-biggest listed platinum group, said the move aimed to protect its 32 percent stake.

"This does not make our policy of being a pure platinum group any different," a Lonmin spokesman said.

As part of the original debt overhaul announced in January, Ashanti bondholders owed about $55 million were going to convert their debt into new Ashanti shares at $3.70 each -- a relatively small discount to the then share price of about $3.90.

But the gold price has surged 14 percent since then, taking Ashanti's shares above $5 and prompting Lonmin to stump up the additional equity itself, rather than see the bondholders making a handsome profit and dilute its holding.

Under the terms of the new plan, Lonmin is to subscribe for the new shares at a price capped at $5.40 each as part of a wider rights issue, the size of which has yet to be determined.

The rights issue is to be launched sometime in the next 18 months and, if taken up, would ensure Lonmin's percentage stake in Ashanti did not jump far above 32 percent -- a level it sees as consistent with its view of the holding as a non-core asset.

Ashanti got into trouble after racking up huge losses on its hedge operations in 1999. The company, which sells gold forward in the derivatives market, almost collapsed that year as rising gold prices left its hedge book in tatters.

The original debt overhaul plan was designed to bolster the company's balance sheet and leave it in better shape to take part in rapid consolidation of the gold industry.

In a side deal, Lonmin has written a call option giving the Ghanaian government, which owns about 20 percent of Ashanti, the right to buy $28.4 million of the new stock.

Lonmin's total $75 million investment is currently held in the form of mandatorily exchangeable notes which are to be converted into new shares at the time of the rights issue.

Ashanti's shares were down 1.4 percent at $5.07 in New York.