The soldiers went on state television to declare they had seized power in protest against the government's failure to quell a rebellion in the north.

Concern over Randgold's Loulo, Gounkoto operations and its joint venture Morila weighed on the gold mining company's shares yesterday.

The Mali operations account for about two-thirds of Randgold production.

CEO Mark Bristow, who is at the Loulo complex, about 350km from the capital, Bamako, said exact details were unclear, but the situation at the flagship mine was calm.

"Malians respect laws and I don't believe this will come with a high-handed change in political direction," Bristow said.

"We don't expect any subsequent governments to disregard proper and due process."

Analysts said Randgold - which also operates in Ivory Coast, Senegal and the Democratic Republic of Congo - had experience dealing with unrest, but said the lack of clarity would hit shares.

"[The] uncertainty will be negative for the share price as Randgold's Malian operations represent 43% of the group net present value and 65% to 70% of group production in 2012," an advisory group said.

Other miners with significant operations or exploration projects in Mali include IAMGold and Cluff Gold - with the latter down 9.4% - while AngloGold and Gold Fields are also working in the country.

AngloGold said it was monitoring the situation, but its operations had not been affected.

Mali is one of the most significant gold producers in Africa, alongside Ghana and South Africa, and gold is one of the country's top exports.