The Nicaraguan authorities and paramilitary groups working with them have killed, tortured, raped and forcibly disappeared anti-government protesters, creating a climate of fear that is driving thousands of people to flee the country, the United Nations has said.

“Repression and retaliation against protesters continues in Nicaragua as the world looks away,” said Zeid Ra’ad al-Hussein, the UN human rights chief, in a statement on Wednesday.

About 300 people have died and more than 2,000 have been injured as the authorities resort to multiple forms of repression – including extrajudicial killings, widespread arbitrary detentions and the ferocious intimidation of critics – to curb protests in the past five months, according to a report released by the rights agency.

In one of his last official appearances before stepping down as high commissioner for human rights, Mr Hussein called for action by the UN Human Rights Council and the international community to prevent the country from plunging into deeper social and political turmoil.

“Any action should ensure full accountability for abuses,” he said. Nicaragua’s president, Daniel Ortega, who first came to power leading Marxist guerrillas against the dictatorship of Anastasio Somoza, has denied government responsibility for the turmoil.

Excessive force In a statement, the Nicaraguan government denied using excessive force against protesters or engaging in repression. It dismissed the UN report as “subjective, slanted, prejudiced and notoriously biased, drafted under the influence of sectors linked to the opposition”.

It also complained that UN investigators ignored the Ortega administration’s claim that the violence and disorder described in the report did not unfold in the context of “social protests”, but rather as part of “an attempt at a coup d’état aimed at breaking the constitutional order”.

The crisis in Nicaragua started as modest protests by environmentalists, students and rural communities over the government’s slow response to forest fires in southern Nicaragua in April. They quickly escalated into demands for Mr Ortega to step down when the government announced social security changes that raised workers’ contributions and cut pensions for retirees.

As students marched in the capital, Managua, and in provincial towns, armed paramilitary groups known as “shock forces” or “mobs” began attacking protesters. The police, using live ammunition and snipers, shot demonstrators, some fatally, the UN said in the 41-page report.

These “shock forces” were reported to be “well-trained and equipped with vehicles, military equipment and weapons, including with high-calibre arms such as the AK47 and Dragunov sniper rifles”, the report said. They typically arrived in pick-up trucks escorted by police, dressed in balaclavas and identically coloured clothing, and then opened fire at random or targeted demonstrators.

Attacks by pro-government gangs on Mother’s Day marches, which were held in support of mothers whose children had been killed in earlier protests, ended in 15 deaths and 199 injuries, the report said.

Barbed wire Some anti-government protests were violent, but UN officials said there was no evidence they had been co-ordinated. By contrast, the “shock forces” were found to have often acted jointly or in co-ordination with security forces. Detainees have been shocked with Tasers and tortured with barbed wire and attempted strangulation, the UN rights office said. Women and men have been raped, including with rifles and other objects, it said, and threats of sexual violence against people in detention have been common.

The number of protests has fallen off in recent weeks, “which indicates the chilling effect of repression”, the report said. The level of persecution, with arbitrary dismissal of civil servants and intimidation of anyone linked to protests or defending the right to demonstrate, has forced many into hiding or to flee the country, Mr Hussein’s office said.

It has also started to stoke concern in a region already grappling with the impact of Venezuela’s political and economic crisis. The Organisation of American States created a working group this month to monitor developments in Nicaragua, the first time it has taken such action on a member state.