The military spokesman was not available to comment.
Mr Mnangagwa's downfall opens the way for his arch rival, Mr Mugabe's 52-year-old wife Grace, to take power when the ailing president dies, resigns or is ousted. Whilst reports on social media seem to imply that a coup is underway, Khuluma Afrika understands that military presence has been increased there to improve security in the face of growing uncertainty in the country.
Today, four tanks were seen moving towards Harare, while two other tanks were seen parked beside the main road from Harare to Chinhoyi, 14 miles from the city, pointing in the direction of the capital.
Addressing a press conference in the capital, Chiwenga, a perceived Mnangagwa loyalist, said the purges must stop.
"It's clear we are entering new territory here".
His lengthy rule has been marked by brutal repression of dissent, mass emigration, vote-rigging and economic collapse since land reforms in 2000.More news: Qualcomm rejects $130 billion Broadcom bid
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In a rare statement that highlighted the tensions rising in the impoverished southern African nation, General Constantino Chiwenga, commander of Zimbabwe Defence Forces said there was instability in ZANU-PF, which was causing anxiety in Zimbabwe.
Chiwenga also vowed military intervention to stop "counter revolutionaries" who had hijacked ZANU-PF and seeking to destroy it from within.
The crisis marks an "ominous moment in the ongoing race to succeed" Mugabe, said political analyst Alex Magaisa in an online article.
"As a result of squabbling within the ranks of Zanu-PF, there has been no meaningful development in the country for the past five years".
Although the ruling ZANU-PF party has said it would never succumb to military pressure.
Chiwenga's remarks came after President Robert Mugabe last week fired Vice President Emmerson Mnangagwa, his political ally for more than 40 years, on allegations of disloyalty and deceit.
Grace, now poised to become a vice president, did not fight in the liberation war.