A government-appointed human rights group in Zimbabwe has accused soldiers of using "systematic torture" in a crackdown on protests.
The Zimbabwe Human Rights Commission strongly criticised authorities for using troops to quell demonstrations.
Unrest broke out more than a week ago following a sharp rise in fuel prices.
Reports have emerged of assaults allegedly carried out by the military in various parts of the capital, Harare.
The continuing violence raises further questions about President Emmerson Mnangagwa's control over the military, which helped to bring him to power 14 months ago, our correspondent adds.
President Mnangagwa has promised that abuses against civilians will not be tolerated.
In a blunt statement, the commission said at least eight deaths had been reported since last week, "mostly attributed to use of live ammunition".
On Monday Mr Mnangagwa, 76, broke off a trip to Europe to deal with the continuing unrest.
He had been due to attend the Davos economic summit where he was expected to seek investment for Zimbabwe.
Back in Harare, he took to Twitter to urge all sides to work together to fix a broken economy.
In a series of tweets, he said violence or misconduct by security forces was "unacceptable and a betrayal of the new Zimbabwe", adding: "If required, heads will roll.
How did the protests start?
Mr Mnangagwa announced a steep increase in the fuel price earlier this month.
The price rises were meant to tackle fuel shortages, but mean that Zimbabwe now has the most expensive fuel in the world, according to GlobalPetrolPrices.com.
Many Zimbabweans, worn down by years of economic hardship, have suddenly found they cannot even afford the bus fare to work.
This led to angry protests in Harare and the south-western city of Bulawayo.