Zimbabwe's main opposition party says the ruling party has put a "full stop" to power-sharing talks by carrying out a new wave of violence.

In a statement Thursday, the Movement for Democratic Change (MDC) accused ZANU-PF thugs of attacking opposition supporters in Harare and other cities, and setting up what the opposition said were two torture bases in the capital, Harare.

It said ZANU-PF's actions violate a basic power-sharing agreement signed in September and have killed the dialogue on forming a unity government.

Movement for Democratic Change leader Morgan Tsvangirai addresses supporters during rally in Masvingo, 19 Oct 2008

It was not immediately clear if MDC chief Morgan Tsvangirai still plans to attend a summit on the Zimbabwe crisis to be held in South Africa on Sunday.

The talks between Tsvangirai's party and ZANU-PF have been stalled for weeks because of disputes over who will control key cabinet ministries.

South Africa's government has said it is concerned at the slow pace of the talks and would push for a final agreement at Sunday's conference, hosted by the Southern African Development Community.

The use of force against Zimbabwean opposition activists has been widely documented by human rights groups.  In 2007, police beat and injured Tsvangirai at a rally in Harare.    In June of this year, Tsvangirai pulled out a presidential run-off election against Mr. Mugabe after dozens of MDC activists were killed and hundreds more injured by ZANU-PF militants.

Many government later dismissed the run-off, won by Mr. Mugabe, as a sham.

Despite the violence, ZANU-PF and the MDC are under pressure to strike a deal so Zimbabwe can recover from its deep economic crisis.  Inflation is officially estimated at 231 million percent, though analysts say the actual figures is even higher.