ACCRA, Oct 12 (Reuters) - Ghana's president, Jerry Rawlings, sacked his mining and energy minister Fred Ohene-Kena on Tuesday, state radio reported, quoting a statement from the presidency.

The statement gave no reason for the move, which coincided with a conditional bid for troubled Ghanaian mining company Ashanti Goldfields Co Ltd from Lonmin Plc. Ohene-Kena was in London in connection with the bid, officials said earlier.

The sale of government shares in Ashanti, Ghana's biggest company, quoted on the London, New York and Accra stock exchanges, is a sensitive issue in the West African nation. The government, which has a 20 percent stake, must approve any deal.

Ohene-Kena expressed general support for the idea in an interview with the pro-government Daily Graphic newspaper on October 8. ``Such a merger will enable AGC to become a bigger entity and have a competitive edge over other mining companies,'' he said.

Ashanti, Africa's third largest gold producer -- which is struggling to resolve a crisis on its gold hedge book -- said on Tuesday shareholders should exercise ``extreme caution'' since there was no assurance that a definitive merger proposal would be made.

Lonmin on Monday made a conditional all-share offer for Ashanti, in which it already has a 32 percent stake, valuing the company at nearly $840 million, based on current share prices.