The leader of the opposition Democratic Alliance (DA) Mmusi Maimane has called for Zimbabwean president Robert Mugabe to step down and for free and fair elections to be held immediately.

The Zimbabwean military has taken control of the capital Harare as well as state broadcasters, fuelling speculation of a coup against 93-year-old Mugabe. The military has said it is acting against “criminals” surrounding the ageing leader but a military spokesman has denied that this amounted to a coup.

Maimane said on Wednesday: “The current instability in Zimbabwe must be a cause for concern for all African countries who stand for democracy on the continent. According to reports, the Zimbabwean Defence Force has moved into the country’s capital, Harare, to ‘target criminals’ aligned to President Robert Mugabe – the first signs of what appears to be a military coup”.

“We therefore call for fresh elections to be held in Zimbabwe as soon as practically possible, and for Robert Mugabe to immediately resign as President of Zimbabwe. This will allow the people of Zimbabwe to choose a new direction for their country, and to free themselves from the tyrannical reign of Robert Mugabe and his Zanu-PF. True democracy is adhering to the will of the people, not the internal politics and arrangements of liberation movements,” Maimane said in a statement.

He also urged South African Minister of International Relations and Cooperation Maite Nkoana-Mashabane to brief the South African public on the extent of the crisis in Zimbabwe, including what action the South African government will take.

“While the involvement of the military in politics is never to be celebrated, it must be noted that the original sin in the sad collapse of Zimbabwe was the South African government’s failure, under President (Thabo) Mbeki, to stand up for democracy and enforce the results of the 2008 election. Allowing Mr Mugabe to remain in office even after losing an election clearly sowed the seeds for what we are seeing today.”

These latest events followed Mugabe’s decision to fire his Vice President Emmerson Mnangagwa last week in an ongoing struggle for party leadership within the ruling ZANU-PF.