Mwana Africa, the miner run by Oliver Baring, lost a third of its value after it said that it was gambling its dwindling cash pile on reopening a mothballed goldmine in Zimbabwe.

The company said that the restart of the Freda Rebecca mine, planned for September, “could significantly erode the forecast cash position” if there were delays or if the gold price falls, which casts “significant doubt” over whether it could continue as a going concern.

Mr Baring believes that Zimbabwe’s economy shows signs of improving after the power-sharing deal with President Mugabe.

Mwana, down 2.68p at 5.32p, has only £14 million cash left from two successive share issues, having consumed £20 million during the year. It has also mothballed a Zimbabwean nickel mine that ran into production problems and the company is examining whether it can reopen the mine using lower-cost production techniques.

Lupus Capital fell 7¾p to 14½p as Greg Hutchings, its founder, left the industrial group, after agreeing a costly debt refinancing with banks.

Valiant Petroleum rose 53p to 520p as it and Petrofac, its partner in the Don Southwest field in the North Sea, began to pump oil from the field. The two also said that they had struck oil in a side well, expanding the potential size of the reservoir.

Braemore Resources rose 0.52p to 5.05p after it increased its attractions to Ruukki, its potential predator, by extending the terms of its licence on ConRoast smelting technology, which can cope with a wider range of platinum ore than traditional furnaces.

Hampson Industries rose 4¾p to 72½p after it agreed a deal with Advanced Integrated Technology, of the United States, to supply equipment for a new business jet.

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