Updated

HARARE, Zimbabwe-- The U.S. Embassy in Zimbabwe on Friday criticized police and judicial officials for failing to stop escalating political violence, as a human rights group said it had documented more than 20 cases a day of assault, intimidation and torture.

In a statement, the embassy said that militants backing longtime President Robert Mugabe's ZANU-PF party had created a climate of fear and intimidation, particularly in the western Harare township of Mbare. The militants there are "unrestrained" by police and are extorting local traders, it said.

ZANU-PF as a party committed to violence and intimidation unconstrained by the laws of the land," the U.S. Embassy said.

The independent humans right group Zimbabwe Peace Project, meanwhile, said 85 percent of the violence it had documented in August was perpetrated by Mugabe supporters. The group's researchers detailed assaults, intimidation and torture, as well as politically motivated theft and looting.

About 10 percent of 702 violations in the period under review were blamed on activists of Prime Minister Morgan Tsvangirai's party. Tsvangirai, a longtime opposition leader, joined into a power-sharing agreement with Mugabe in 2009 that continues to fray.

Mugabe has called for elections in March to end the coalition formed after disputed, violence-plagued elections in 2008.

Tensions also have been rising within the ZANU-PF party itself following the death of party powerbroker Gen. Solomon Mujuru, the Zimbabwe Peace Peace Project bulletin said. Mujuru died in a a fire at his home almost two months ago, renewing rivalries over who will succeed the 87-year-old Mugabe.

Police have refused to release details of investigations into the fire that burnt Mujuru beyond recognition. His burial at a national shrine outside Harare was by far the biggest funeral since independence in 1980, attended by some 50,000 mourners.

Many Zimbabweans believe the fire was intentional, and it's feared political unrest could erupt if it emerges the popular former guerrilla leader was murdered.