The Human Rights Forum, a collective of local groups, said it had received reports that five people had sustained gunshot wounds.

Riot police patrolled downtown Harare as army helicopters circled above. Businesses closed early and schools called parents to pick up their children, fearing violence.

The main labour union called for a three-day stay-at-home strike starting Monday; central Harare was deserted by 4pm, Harare time, with commuters walking home from the city centre because there was no public transport.

Mnangagwa defended his fuel policy, saying prices in Zimbabwe were the lowest in the region.

"Zimbabwe is going through both political and economic reforms and these do not come easily. It will take time for things to settle and results to be shown," he told reporters in Moscow at the start of a five-nation foreign trip.

Cash shortages have plunged the economy into disarray, threatening widespread social unrest and undermining Mnangagwa's efforts to win back foreign investors who left under former president Robert Mugabe, whose 40-year rule ended in a coup more than a year ago.

Everyday life is becoming increasingly difficult, with the prices of basic goods spiralling and medical supplies in short supply. Motorists have had to wait for hours to fill up their vehicles at fuel stations, where soldiers are often deployed to break up fights over who is next in line.

Zimbabwe – which now uses the US dollar after abandoning its currency in 2009 following hyperinflation – plans to introduce a new currency in the next 12 months.

But Zimbabweans are still traumatised by hyperinflation, which hit 500 billion per cent in 2008 and left the local currency worthless, wiping out savings and pensions. Inflation reached 31 per cent in November, the highest in a decade.

Reuters