Vast Resources said chief executive Roy Pitchford had resigned, effective December 31, as the company's focus had shifted to Romania from Zimbabwe.
He would be replaced by Andrew Prelea, currently president of the company's Romanian subsidiary.
"When Roy joined the board three years ago, Vast was almost exclusively focussed on Zimbabwe, his country of birth and a place that he continues to feel very passionately about," Vast chairman Brian Moritz said.
"Over subsequent years our focus has increasingly turned to Romania and it is this change that has prompted Roy to step down as CEO, to be replaced by Andrew."
At 9:53am: (LON:VAST) Vast Resources PLC share price was +0.02p at 0.58p