Zimbabwe was on edge Tuesday as armoured personnel carriers were seen outside the capital and the ruling party accused the army commander of treasonable conduct.

The Associated Press saw three armoured personnel carriers with several soldiers in a convoy on a road heading towards an army barracks just outside the capital, Harare.

While it is routine for armoured personnel carriers to move along that route, the timing heightened unease in the southern African country that for the first time was seeing an open rift between the military and 93-year-old President Robert Mugabe.

The scene in Harare, where armoured personnel carriers were spotted The scene in Harare, where armoured personnel carriers were spotted (Tsvangirayi Mukwazhi/AP)

The military has been a key pillar of Mugabe’s power since independence from white minority rule in 1980.

Mugabe last week fired vice president Emmerson Mnangagwa and accused him of plotting to take power, including through witchcraft.

Mr Mnangagwa, who enjoyed the backing of the military and was once seen as a potential successor to Mugabe, fled the country and said he and his family had been threatened.

More than 100 senior officials allegedly supporting him have been listed for disciplinary measures by a faction associated with Mugabe’s wife, Grace Mugabe.

Zimbabwe's army commander Constantino Chiwenga has criticised the instability in the country’s ruling party (Tsvangirayi Mukwazhi/AP)Zimbabwe’s army commander Constantino Chiwenga had threatened to “step in” to calm political tensions (Tsvangirayi Mukwazhi/AP)

The first lady, whose political profile has risen in the past few years, now appears positioned to replace Mr Mnangagwa at a special conference of the ruling party in December, leading many in Zimbabwe to suspect that she could succeed her husband as president.

On Monday, army commander Constantino Chiwenga issued an unprecedented statement saying purges against senior ruling Zanu-PF party officials linked to the 1970s’ liberation war should end “forthwith”.

“We must remind those behind the current treacherous shenanigans that when it comes to matters of protecting our revolution, the military will not hesitate to step in,” the army commander said.

The state-run broadcaster did not report on his statement.

The ruling party’s youth league, aligned to the first lady, on Tuesday criticised the army commander’s comments, saying youths were “ready to die for Mugabe”.

On Tuesday night, the ruling party issued a statement accusing the army commander of “treasonable conduct”, saying his comments were “clearly calculated to disturb national peace and stability” and were “meant to incite insurrection”.