Politicians in Burundi have overwhelmingly voted in support of a plan to withdraw from the international criminal court in what would be an unprecedented move for any country.

The decision escalates a bitter dispute with the international community over the human rights situation in the east African country, which has experienced more than a year of deadly violence since its president, Pierre Nkurunziza, made a decision to pursue a third term.

According to the Coalition for the International Criminal Court, no state has ever withdrawn from the ICC, which prosecutes cases of genocide, war crimes and crimes against humanity.

Out of 110 Burundian politicians, 94 voted in favour of the withdrawal plan, months after the ICC announced it would investigate the country’s ongoing violence.

Some African countries have threatened a withdrawal from the Rome statute, the treaty that created the ICC, accusing the court of disproportionately targeting the continent. Only Africans have been charged in the six cases that are ongoing or about to begin, though preliminary ICC investigations have been opened elsewhere in the world.

Members of Burundi’s parliament raise their arms to vote in Bujumbura on Wednesday. Photograph: Onesphore Nibigira/AFP/Getty Images

Of the 124 countries that are parties to the Rome statute, 34 are African, the largest continental bloc. The US is not a party to the treaty.

Burundi’s decision is not immediate. Observers say a country wishing to withdraw from the ICC must write to the UN secretary general stating its intention, and the withdrawal takes effect a year after the letter is received.

Vital Nshimirimana, a Burundian rights activist, urged the UN to challenge the government’s decision. “Already, we have information that intelligence agents are torturing, killing Burundians behind closed doors,” he said. “The world ought to rescue the people of Burundi.”

Burundi’s government has repeatedly said it is the victim of propaganda by exiles and opponents who want to diminish its credibility.

Hundreds have died in Burundi since Nkurunziza last year pursued and won a third term that many have called unconstitutional. Since his candidacy was announced in April 2015, there have been violent street protests, forced disappearances and assassinations. More than 260,000 people have fled.

On Monday, Burundi’s government banned three UN human rights investigators from entering the country following the release of a report that cited massive rights violations allegedly perpetrated by security agencies.

The push among some African countries to withdraw from the ICC began after the court indicted the Kenyan president, Uhuru Kenyatta, on charges of crimes against humanity for post-election violence in 2007 in which more than 1,000 died. The ICC prosecutor said threats to witnesses, bribery and a lack of cooperation by Kenya’s government led to the case’s collapse.

Some countries have called for a separate African court with jurisdiction over rights abuses.