The youth wing of Zimbabwe's ruling party has said it is "ready to die" for President Robert Mugabe, following a threat by the military to intervene if a purge of former war fighters continues.

Kudzai Chipanga, leader of the ZANU-PF party's Youth League, said on Tuesday that they would not allow the army to choose the country's leaders amid rising tensions in the wake of Mugabe's firing of his vice president.

"We will not fold our hands to allow a creature of the constitution to subvert the very constitution which establishes it," Chipanga told a press conference in the capital, Harare.

"Defending the revolution and our leader and president is an ideal we live for and if need be it is a principle we are prepared to die for," he added.

'The military will not hesitate to step in'

Chipanga's statement came a day after army commander Constantino Chiwenga said in a rare statement that the targeting of senior ZANU-PF officials with a "liberation background must stop forthwith."

Vice President Emmerson Mnangagwa, an ally of the army chief and a veteran of the country's struggle for independence, was sacked last week by 93-year-old Mugabe for showing "traits of disloyalty".

Mnangagwa was seen as a likely successor to the ailing president, and his ousting now appears to pave the way for First Lady Grace Mugabe - who is backed by ZANU-PF's Youth League - to succeed her husband.

"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," Chipanga warned in his statement on Monday.

As the political crisis deepens, witnesses on Tuesday reported seeing several tanks heading towards Harare, according to news agencies' reports.

Both President Mugabe and First Lady Grace Mugabe are yet to publicly comment on the threats from the military, which has backed Zimbabwe's leader throughout his 37 years in office.

The opposition Movement for Democratic Change (MDC) on Tuesday called on people to defend the civilian rule in the country following the army's threat.

'Leadership contest'

Lance Guma, a political analyst and broadcaster based in Britain, said the threat from the military is the biggest challenge Mugabe has faced during his nearly four decades in power.

"The army is flexing its muscles," he told Al Jazeera.

"They are telling the civilian government that the army is the real power in the country," added Guma.

"But I don't think there is an appetite for coup. The region will not accept that."

ZANU-PF has ruled the country since it gained independence from Britain in 1980, and analysts claimed that that is not about to change.

"The dominance of ZANU-PF on the political landscape in Zimbabwe is not in question," George Shire, a political analyst, told Al Jazeera.

"What you see is really a leadership contest taking place - Zimbabwean style," added Shire.

Zimbabwe's armed forces have always maintained that they will only back candidates to succeed Mugabe who fought in the country's independence war. Grace Mugabe, 52, is a not a war veteran.

ZANU-PF is expected to hold a conference in December.