Global miners Rio Tinto Plc (RTP) and BHP Billiton Ltd. (BHP) said Wednesday they were closely watching the deteriorating political situation in Guinea but hadn't yet decided to move workers out of the country for safety reasons.

Rio employs fewer than 100 expatriate staff and "a few hundred" Guinean nationals in the West African state, where the company is conducting work on the Simandou iron ore project, one of the world's largest undeveloped iron ore deposits.

Military junta troops on Tuesday shot and killed at least 157 people and wounded more than 1,000 while breaking up a protest rally at a stadium in Conakry. There were also reports of civilian deaths outside of the capital.

"The safety of our workforce is our immediate focus. We have arrangements in place. There hasn't been a decision to fly people out," Rio iron ore spokesman Gervase Greene told Dow Jones Newswires.

A spokeswoman for BHP Billiton said all of its staff in Conakry and staff at joint venture sites "have been accounted for and are safe."

BHP is considering developing a US$4.8 billion alumina refinery in the country, which holds about one-third of the world's known bauxite reserves, in partnership with New York-based Global Alumina Corp. (GLA.U.T)

Protesters gathered in the stadium to oppose any bid by the junta leader to run for president in an election due in January.

Captain Moussa Dadis Camara took power in December last year after leading a bloodless coup within hours of the death of Guinea's strongman leader Lansana Conte, who had ruled the west African country since 1984.

The United Nations, African Union and European Union have all expressed alarm over the violence.

Guinea's recent calamitous political history highlights the risks of committing to multi-billion mining projects in unstable jurisdictions.

Also in December, but prior to the ousting of the government, Rio's plans for the project were thrown into disarray when the government stripped it of the northern half of the mining concession, handing it to BSG Resources Guinea, a subsidiary of Israeli businessman Benny Steinmetz's BSG Resources.

"We're waiting for greater clarity on the status of our mining concession. There hasn't been any change for several months but we're confident of the legality of our concession," said Greene.

Other miners active in Guinea include Alcoa Inc. (AA) and United Company Rusal. Both operate bauxite and alumina operations in the country.

Earlier this month, Rusal received a court order canceling the 2006 purchase of the Friguia operation. Rusal argues it has bought Friguia in full compliance with Guinean legislation, and has appealed against the ruling.

In 2007, both Rio and BHP evacuated workers after then president Conte declared martial law to quash a violent uprising.

-By Elisabeth Behrmann, Dow Jones Newswires;

61-2-8272-4689 elisabeth.behrmann@dowjones.com