Amnesty International charged yesterday that although Uganda President Idi Amin has declared 1978 a year of "peace and reconciliation" the patterns of arbitrary arrests, disappearances, torture and killings "persist unaltered" under his dictatorship.

The human rights monitoring group that was awarded the 1977-Nobel Peace Prize said that from 50,000 to 300,000 people have been arbitrarily killed in the African nation since Amin came to power in 1971.

Unless International pressure is increased on Uganda "there is good reason to fear" that human rights violations of the same scale "continue for along time to come," the volunteer group said in a report to the Senate subcommittee on foreign economic policy.

The report was released as the Senate was urged to bar U.S. coffee imports from Uganda in an effort to topple Amin's regime.

"I feel very strongly that this nation cannot sit idly by while genocide is being practiced in Uganda," Sen. Frank Church (D-Idaho) said in opening three days of hearings on the matter.

"It appears that trade with the U.S. may be an important factor in maintaining the economic viability of the Amin government," Church said at another point.

Coffee is Uganda's only major export. In 1977, the United States imported about one-third of the coffee produced in the country. Britain imported about 20 per cent.

On Monday, the House approved a resolution urging the Carter administration to ban all trade with Uganda. The resolution, however, is not binding on the president and fall short of the mandatory sanctions being urged by Sen. Mark O. Hatfield (R-Ore.) and other members of Congress.

Both Hatfield and Church yesterday praised Procter & Gamble and Hills Brothers for deciding to stop buying Uganda coffee. Two other companies, General coffee for resale in the United States, but are continuing to purchase it for foreign markets.

Hatfield critized the Carter administration, the United Nations and Third World countries for their reluctance to act on the Uganda government. Amin, he said, is guilty of the "most flagrant forms of genocide against his own people."

"We're led to believe that a ban on coffee imports could lead to a toppling of his regime," Hatfield said in an interview.

Amin has declared he has turned over a new leaf, and has invited Hatfield and other officials to have dinner with him - an invitation Hatfield has declined.

Amnesty International said it could find little evidence of any real change in Amin. Its study reported on 847 known killings since the beginning of 1977, including some as recent as April.

Although there have been periods during that time when killings temporarily dimished, the group said, "The Uganda govenment has taken no steps to improve the human rights situation."

Every new crisis, it said, brings on a new wave of random arrest and killings. Politicians, businessmen, writers, academics, foreigners and religious leaders have been particularly singled out, it said.

The government, it added, has "institutionalized" various forms of torture, including gouging out eyes and electric shock treatments.

In some cases, arrested prisons are ordered at gunpoint to murder other prisoners by hitting them on the head with a hammer, ax or car axle, the report said. "In one version of this grotesque and common method of killing, detainees are lined up: the first man is given a hammer to kill the next man, he is then in turn, killed by another man, until the whole line is killed, the last survivor being shot."