PARIS, Dec 4 (Reuters) - French nuclear fuels company Orano said on Wednesday that authorities in Niger have taken control of its Somair uranium mine as the military-led government steps up pressure on foreign investors in the West African country.

Orano, which owns about 63% of the mine, said in a statement that decisions taken at Somair board meetings were no longer being applied. Niger owns the remaining stake in Somair.

"Orano is today confirming that Nigerien authorities have taken operational control of the company," it said.

The business climate for international companies in Niger, which accounts for about 4% of global output of uranium, has become uncertain after a military coup last year.

Uranium is the most widely used fuel for nuclear energy and Orano, which has operated mines in Niger for years, vowed to "defend its rights before competent bodies" in order to allow Somair to operate normally, without giving details.

Officials at the Niger embassy in Paris did not immediately respond to a request for comment from Reuters.

Niger accounted for about 15% of Orano's uranium supplies when its mines were operating at full capacity. The company has said the halt in exports from Niger has been fully offset by a ramp-up of mines in Canada and Kazakhstan.

In June, Orano said Niger had removed a mining permit for its Imouraren subsidiary. Canada's GoviEx Uranium (GXU.V) said it had been stripped of its right to develop a uranium project in Niger in July.

Orano said it has been warning for several months of interference in governance at Somair, where it was forced to suspend production after authorities halted exports last year.

It said a resolution adopted by the Somair board on Nov. 12 to suspend expenditure related to production to preserve funds for salaries was being deliberately ignored and this was "further deteriorating the company's financial situation".