Cargill Inc. has suspended operations at a sunflower-oil plant in the Donetsk region in eastern Ukraine, where the government is battling pro-Russian separatists, and said the facility has been occupied by armed individuals.

The plant was shut July 4 because of an "escalation of tension in the region," Anastasia Dudley, a spokeswoman for Minnetonka-based Cargill, said Thursday.

"The plant has subsequently been occupied by a small number of armed individuals whose intentions are not clear to us," Dudley said in an e-mail.

No Cargill employees are currently at the site, and it's unclear when it will restart, she said.

Ukrainian forces are advancing after rebels shifted thousands of fighters to the provincial capitals of Donetsk and Luhansk, Andriy Parubiy, head of the country's national security and defense council, said on Wednesday. As many as 100,000 inhabitants have fled Donetsk in recent weeks, according to the mayor's office.

Cargill, the largest closely held firm in the United States, has been present in Ukraine for 21 years, and has more than 700 employees there.

Cargill bought a 5 percent stake in UkrLandFarming PLC, Ukraine's biggest agricultural company, for $200 million in December. UkrLandFarming CEO Oleg Bakhmatyuk said July 1 that he was postponing a planned initial public offering of shares in his company because of political violence.

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