The fragile state of Zimbabwe's economy was also in focus as President Emmerson Mnangagwa headed home early from a foreign trip during which he had been expected to pitch for investments.

In addition, South Africa said it turned down a request from its neighbour for a $US1.2 billion loan last month.

The lawyer for pastor Evan Mawarire, a rights activist, said he would seek bail at the High Court after being charged with subversion.

Mawarire is the most prominent of hundreds of people, also including four opposition lawmakers, detained on public order charges on Friday following violent protests last week against a fuel price rise.

Police say three people died during the unrest, but lawyers and human rights groups say evidence suggests at least a dozen were killed.

Mnangagwa's spokesman said on Sunday that the crackdown was a foretaste of how authorities would respond to future unrest.

In what opponents view as a further attempt to crush dissent, the government has imposed a sporadic internet blackout since Tuesday.

A lawyers' group said it planned to challenge that shutdown in the High Court on Monday afternoon.

The action is directed at Zimbabwe's three mobile networks as well as Mnangagwa, the national security minister and the head of the intelligence services.

Australian Associated Press