Nkomo, 78, was nominated for the joint number two position alongside Joice Mujuru two years ago after a fractious meeting of the southern African nation’s ruling ZANU-PF party.
“We’ve lost our vice president John Landa Nkomo. He was suffering for a long time with cancer. All of a sudden now we heard his situation had become worse … deteriorated from yesterday,” a somber Mugabe told reporters at his official residence.
A founding member of nationalist leader Joshua Nkomo’s ZAPU before its merger with Mugabe’s ZANU-PF in the 1980s, Nkomo was seen by many as an efficient administrator but an unlikely potential successor to Mugabe due to his age and ill health.
Analysts say his death will rekindle debate over 88-year-old Mugabe’s health issues and open up a succession battle as the country’s shaky coalition government edges towards a general election due this year.
Mugabe vowed in December to fight like a “wounded beast” to retain power amid grumbling within his party that he should hand over the reins to a younger leader.
He is Africa’s oldest head of state and has ruled the former British colony since independence in 1980.
There has been widespread speculation about his health but Mugabe and the government have denied reports he has been receiving treatment for prostate cancer in Singapore over the last two years.
Official media were silent on Nkomo’s death but the U.S. embassy released a statement offering its condolences at the passing of “a patriot who dedicated his life to Zimbabwe’s sovereignty and prosperity”.
Mugabe and ZANU-PF are struggling to shore up support among young voters, who care more about the economy than the party’s role in leading the 1970s liberation struggle against white-minority rule.