A leading human rights group accused Zimbabwe's government of using its army and ruling party militants to unleash "terror and violence" on dissenters, particularly those seen as traitors to Robert Mugabe.

In a statement Wednesday, New York-based Human Rights Watch joined other rights groups and Zimbabwe's opposition party in linking violence since last month's presidential vote to the security forces and so-called "war veterans" — groups loyal to Zimbabwe's autocratic President Mugabe.

A Human Rights Watch researcher who returned Monday from a two-week fact-gathering trip to Zimbabwe said the worst violence was in traditional strongholds of Mugabe's party, where voters in recent years have increasingly turned to the opposition Movement for Democratic Change.

The violence "is a form of punishment of people who turned against the ruling party," Tiseke Kasambala told reporters in Johannesburg on Wednesday. "The government is actually focusing on its strongholds and some of the areas it thinks it should have won."

She also said that in the last four days, Human Rights Watch had received reports that more than 100 polling station officers — most of them teachers and low-ranking civil servants — had been detained in an eastern province. She described that as another indication the government and its loyalists were targeting those seen as betraying Mugabe.

Mugabe's administration has countered that the opposition groups are responsible for the violence. Attempts to reach Zimbabwean officials for comment Wednesday were not immediately successful, and Kasambala said Wednesday she had not yet put her findings to the Zimbabwean government.

"They have been claiming they don't have evidence of this violence we've been talking about," she added. "But it's there — in the hospitals."

Mugabe has been accused of using violence and intimidation and plotting fraud to hold onto power after March 29 presidential elections he is believed to have lost.

Results from those elections have yet to be released, and ruling party officials have said a runoff would likely be necessary. Opposition candidate Morgan Tsvangirai says he won outright; independent observers say Tsvangirai won the most votes, but not the 50 percent plus one vote needed to avoid a runoff.

Kasambala said she and colleagues interviewed more than 40 "victims of organized violence" — people beaten with iron and wooden clubs, burned and stabbed — in Harare, Zimbabwe's capital, and traveled to outlying areas to interview about 20 others.

"This violence is not only horrific, but it's very well-organized and targeted," Kasambala said.

She said Human Rights Watch had confirmed two deaths, but was concerned the numbers of dead, injured and displaced could be much higher, particularly in northern, traditionally ruling party areas she said had been virtually cut off, with military road blocks keeping inhabitants from leaving and outsiders, including humanitarian workers, from entering.

Kasambala said witnesses had seen senior military officials arming civilians and working with war veterans and other ruling party militants to direct the violence, including setting up torture camps. Witnesses had described soldiers "rampaging" in opposition strongholds in Harare, where an informal curfew was in place, Kasambala said.

Kasambala called on the African Union and the United Nations to intervene to protect Zimbabweans.

The opposition — which Kasambala said was in "disarray" in Zimbabwe because of the violence, its senior officials in hiding or jail — also has appealed to African leaders and to the U.N. for help.

On Tuesday, a Zimbabwe opposition leader urged the U.N. Security Council to appoint a special envoy to his country. But the deeply divided council, which was briefed on situation behind closed doors, took no action.

While the United States, Britain and France back council engagement and sending a U.N. envoy to Zimbabwe, diplomats said South Africa, Russia, China and other members oppose any action now.

In the hearing, Britain's deputy U.N. ambassador, Karen Pierce, said U.N. political chief B. Lynn Pascoe had spoken of "a level of political intimidation and violence that I think many council members found quite chilling."

Alejandro Wolff, U.S. deputy ambassador, said he was struck by Pascoe's characterization of the situation in Zimbabwe "as the worst humanitarian crisis since independence" in 1980.

Human Rights Watch said war veterans were being given guns and trucks by the army and were "collaborating with the army in unleashing a campaign of terror and violence against (opposition) MDC members and supporters."

Kasambala said the arming of civilians could undermine security in Zimbabwe and across the region in the future, though she said its extent was not yet clear.

The veterans groups are fiercely loyal to Mugabe and have roots in the nation's independence struggle but increasingly include militants too young to have been guerrilla fighters.