Zimbabwe can "forge a new path free of the oppression that characterised [Mugabe's] rule" following his resignation, British Prime Minister Theresa May said on Tuesday evening.
Mugabe, 93, resigned shortly after Zimbabwe's parliament began an impeachment process to end his 37-rule as head of state.
May said the "desire of the Zimbabwean people for free and fair elections" has been seen in recent days, along with the desire for an opportunity to "rebuild the country's economy under a legitimate government".
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Britain, as Zimbabwe's "oldest friend", will do all it can to support the country to help the country achieve "the brighter future it so deserves," she said.
Robert Mugabe, as leader of the Zanu party, won 'British-supervised' independence elections in 1980, following which he was named prime minister. He would subsequently rule the country for nearly four decades.
Zimbabwe celebrates independence from Britain annually on April 18.