President Robert Mugabe is under house arrest in Zimbabwe, South Africa's President Zuma said Wednesday, adding that the country was sending envoys on behalf of the region's bloc after the army apparently took over.

"President Zuma spoke to President Robert Mugabe earlier today who indicated that he was confined to his home but said that he was fine," the South African government said in a statement.

"Zuma, in his capacity as Chair of the Southern African Development Community, is sending Special Envoys to Zimbabwe."
South Africa will send its intelligence and defence ministers, the statement said.

South Africa is Zimbabwe's powerful southern neighbour and is home to hundreds of thousands of Zimbabwean migrants.

It has long pursued a policy of quiet diplomacy with Mugabe as Zimbabwe has previously been engulfed by a string of serious political and economic crises.

Long grip on power

Mugabe's decades-long grip on power was dramatically weakened as military vehicles blocked roads outside the parliament in Harare and senior soldiers delivered a late-night television address to the nation.

"We wish to assure the nation that his excellency the president... and his family are safe and sound and their security is guaranteed," Major General Sibusiso Moyo said, slowly reading out a statement.

"We are only targeting criminals around him who are committing crimes... As soon as we have accomplished our mission we expect that the situation will return to normalcy."

Moyo said "this is not a military takeover of government".

But the generals' actions posed as a major challenge to the ageing Mugabe, 93, who has ruled Zimbabwe since independence from Britain in 1980.

Tensions between the veteran leader and the military, which has long helped prop up his authoritarian rule, have erupted in public in recent days.

The ruling ZANU-PF party on Tuesday accused army chief General Constantino Chiwenga of "treasonable conduct" after he criticised Mugabe for sacking vice president Emmerson Mnangagwa.

There is calm in Harare, despite the presence of troops on the streets.