Governments killed thousands of people during the past year, and nearly half the world's nations held prisoners of conscience, many of them without trial, Amnesty International charged yesterday.

In its annual report for 1984, the London-based human rights organization outlined abuses from Afghanistan to Zimbabwe and 121 other countries around the world.

"The taking of human life by the state must be recognized as an urgent and imperative issue for the international community," Amnesty said. "The exercise of the state power to end a citizen's life strikes at the heart of two of the most fundamental of all human rights: the right to life and the right not to be cruelly treated."

More than 1,500 executions were reported in 1984, Amnesty said, but "the true total was certainly higher."

Deaths under torture were reported in Turkey, Uruguay and Chile.

"Outright political killings, often of unarmed civilians during counterinsurgency operations, took place in Chad, El Salvador, Guatemala, Indonesia and East Timor and Peru," the report said.

"Prisoners were hanged or shot after trials by military or revolutionary courts that fell short of internationally recognized standards for a fair trial in Afghanistan, Angola, Cameroon, Iran and Libya."

Amnesty International, winner of the Nobel Peace Prize in 1977, called attention to abuses in Central America by parties at either end of the ideological spectrum. In its entry on Nicaragua, the report condemned both the Sandinista government for unfair trials of political prisoners and the antigovernment guerrillas for "the reported torture and execution-style killing of individuals captured."

There were reports from El Salvador of killings by opposition groups, Amnesty said, but the organization was more concerned with the government's human rights record.

"As a matter of principle, the organization condemns the torture and execution of prisoners by anyone," the report said. "However, after investigating thousands of killings of noncomabatant civilians over the past five years, Amnesty International has concluded that most were extrajudicial executions committed by government forces."

The United States registered a marked increase in the number of executions in 1984, Amnesty said, putting to death 21 prisoners, the most in one year since 1963. As of Dec. 20, the report said, a record 1,464 prisoners in 33 states were on death row.

In the Soviet Union, Amnesty said it was concerned "that many Soviet citizens were imprisoned or confined in mental hospitals solely for the nonviolent exercise of their human rights."

In the Philippines, the organization said, "the government rarely initiated impartial investigations into . . . alleged violations which included extrajudicial executions, torture and ill-treatment of detainees."

The report called attention to reports of beatings and killings of civilians in Zimbabwe's Matabeleland and death sentences imposed by military courts in Angola.

In its entry on South Africa, Amnesty said "detention without trial was used extensively and there were new allegations of torture and ill-treatment of political detainees."