A new report detailing alleged human rights abuses by the government was released here today and is certain to fuel the growing controversy between Zimbabwe and western critics it contends are conspiring in a smear campaign against it.

The report concludes that abuses -- including summary executions, torture, beatings, arbitrary arrests and officially condoned mob violence -- have occurred "on a significant scale" against members of the Ndebele ethnic minority in the southwestern Matabeleland region.

The study by the Lawyers Committee for Human Rights, a New York-based civil liberties group, contains few new allegations but provides the most detailed look yet published on alleged rights violations here.

It contends that although human rights conditions have improved for a majority of Zimbabweans since the advent of black majority rule in 1980, abuses in Matabeleland have "created an atmosphere of fear and mistrust that will take years to overcome."

The continued use of emergency-powers regulations inherited from the days of white rule, which allow indefinite detention without charge on security grounds, has "seriously undermined respect for the rule of law" and "deeply eroded the professionalism of police investigations," the report said.

While Prime Minister Robert Mugabe's government has begun dismantling the "machinery of racism" that existed during white rule, the report said, it is using tactics such as torture and civilian terror "all but indistinguishable from those used by the regime of former prime minister Ian Smith."

Government spokesmen said they could not comment on the report because Zimbabwe had not officially received a copy. But Michael Posner, the committee's executive director, said by telephone that it had delivered a copy to the Zimbabwean Embassy in Washington and sent 10 more to Mugabe and other Cabinet ministers nearly two months ago.

In the past, the government has denied allegations of torture and other abuses and challenged human rights organizations to produce the names of witnesses.

Home Affairs Minister Enos Nkala, who is in charge of the police, two weeks ago accused Amnesty International, the London-based rights group, of paying political dissidents and murderers for false information. Nkala previously has charged that Amnesty is conspiring with church groups here, American and British diplomats, western journalists and the CIA to smear Zimbabwe and undermine the government.

Today's report concedes that Zimbabwe faces a genuine security problem in Matabeleland, caused by armed dissidents who have waged a campaign of killings and economic sabotage against the government since 1982. Most claim a loose allegiance to opposition leader Joshua Nkomo, the country's most prominent Ndebele politician, although he has denounced their activities.

The government says dissidents have killed at least 600 civilians, including more than 100 officials of the ruling party, and it has held Nkomo and his supporters responsible. Opposition party officials have been held incommunicado for lengthy periods without charges, the report says.

The study, written for the committee by free-lance journalist Bill Berkeley, also gives graphic accounts of five persons, none of them named, who describe their torture at the Stops Camp detention center in Bulawayo by members of the Central Intelligence Organization, a special unit that reports directly to the prime minister's office. It says the most common forms of torture are by submersion in water, electric shocks and beatings with sticks, rawhide whips, tire irons, fan belts and rubber hoses.

It also details the deaths of four persons while in detention, including the 1984 death of Air Force officer Temba Moyo, the son of a prominent black nationalist leader and close friend of Mugabe.

The report blames government soldiers for about 1,500 civilian deaths in Matabeleland in 1983, and "perhaps many more" in the Army's first counterinsurgency crackdown there. It also details two incidents of murder in 1985 that the government attributed to dissidents but that witnesses blamed on government soldiers.

The report also says there is strong evidence of "government complicity" in the abductions early last year of at least 100 Nkomo supporters. Most of the abductees, the report said, "have not been seen or heard from since and are presumed dead."