LONDON (AP) _ A human rights group rebuked Sudan's government for human rights violations, saying in a report Friday that it has carried out mass killings of tribal enemies.

Amnesty International's report said there were ''especially disturbing reports'' of mass killings in the remote southern Nuba mountains, home to the mostly Christian and animist Nuba people.

The Muslim government in Sudan has been accused of massive human rights violations in its fight to contain a rebellion in the predominantly Christian and animist south.

As many as a million people have died from famine and the 10-year-old war between north and south. And 6 million have fled their homes.

Amnesty International said there were reports that hundreds of civilians were executed without trial in the Nuba mountains as recently as late December and early January. The government has targeted the Nuba people as alleged supporters of the Sudan People's Liberation Army rebels.

''The exact scale of these killings is not yet confirmed, but Amnesty International knows of scores of other extrajudicial executions in the Nuba mountains in the past year,'' it said, adding that tens of thousands of Nuba people have been driven from their homes by government forces.

It added that in the remote war zones of southern and western Sudan, ''where the government apparently feels free from international scrutiny, the authorities are flagrant in their disregard for human rights.''

The report said hundreds of people were reportedly killed without trial in the southern regional capital of Juba in mid-1992 ''as government forces 'mopped up''' after rebel incursions.

The authorities have not accounted for over 100 men arrested in Juba around the same time, it said.

Amnesty International added that in the major cities of northern Sudan, which was more open to international scrutiny, ''the government appears to be trying to make repression less visible rather than actually ending it.''

''But there is a continuing pattern of detention without charge or trial of government critics.''

Amnesty International said it had the names of 250 political detainees who have been held without charge in the capital, Khartoum, alone in the past year.

On Jan. 28, it said, Mohamed Abdulsid, the Khartoum correspondent of the international Arabic language daily Asharq al-Awsat, was arrested and the newspaper's offices were closed.

Amnesty International added that Sudan People's Liberation Army also was responsible for abuses.

It said that in January 1992 rebel forces killed 87 civilians at Pagarau in Bahr al-Ghazal state, and in September 1992, SPLA forces murdered three foreign aid workers and a journalist.