Buenos Aires (AFP) - Amnesty International hit out on Thursday at the repression by Nicolas Maduro's government in Venezuela, saying that more people were murdered in the South American country than in some war zones.

Opponents have accused Maduro's regime of the authoritarian oppression of any dissident voices during a four-year recession that has left 87 percent of the population living in poverty, according to a group of leading universities.

Amnesty's report highlighted violence carried out by security forces during operations against criminals in impoverished neighborhoods of Venezuela's biggest cities.

"State officials, adopting military methods, use force in an abusive and excessive manner, in some cases intentionally killing during security operations," said human rights defense organization Amnesty in a statement.

"In cases documented by AI, victims were unarmed. Autopsies revealed bullet wounds in the neck, throat, head. They were killed while on their knees or lying down," said Esteban Beltran, director of Amnesty International Spain.

"The number of murders in Venezuela is greater than those in many countries at war."

Venezuela's murder rate is 89 per 100,000 inhabitants, three times more than crime-wracked neighbor Brazil, said Mariana Fontoura Marques, director of international justice policy at Amnesty International Argentina.

Insecurity "was one of the major reasons Venezuelans gave for leaving the country," she added.

Food and medicine shortages and hyperinflation the International Monetary Fund says will reach one million percent this year have also contributed to the mass exodus.

The United Nations says some 1.6 million people have left Venezuela since 2015, heaping pressure on several nearby countries struggling to deal with a mass influx of migrants.