The apparent African exodus from the international criminal court must be stopped or the most heinous crimes will be allowed to go unpunished, Kofi Annan, the former UN secretary general and one of the ICC’s chief architects, has warned.

Burundi, Gambia and South Africa said this year they would no longer recognise the court’s jurisdiction and announced their intention to quit. They claim the ICC disproportionately targets African leaders. Nine of the 10 cases taken by the court have involved former African rulers.

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Annan’s intervention is designed to influence the annual meeting of the Assembly of States Parties, whose members are signatories to the ICC. He warned the actions of the three African countries risked giving the false impression the entire continent was hostile to the court.

Annan was pivotal to the court’s creation when he was UN secretary general, hosting the inaugural conference in Rome in 1998.

Writing in the Guardian, he says: “Most of the continent’s democratic governments stand by the ICC. I stand by the ICC, because the most heinous crimes must not go unpunished.”

He says Africa “was [the court’s] most enthusiastic supporter” at the ICC’s inception. “Memories of the horrors of the Rwandan genocide were still fresh in our minds. In fact, the first signatory of the treaty was an African country, Senegal. Africa remains the single largest regional bloc, with 34 states party to the Rome statute out of 124,” he writes.

Annan said the focus of the ICC’s work in Africa did not indicate any bias but rather Africa’s willingness to refer cases to it. “Of the nine investigations on the African continent, eight were requested by African states. Six African states referred their own situation to the ICC, and African states voted in support of the UN security council referrals on Darfur and Libya,” he writes.

“Kenya was the only case in Africa opened independently by the court, but it enjoyed the enthusiastic support of a majority of Kenyans. They wanted justice for the 1,300 people killed and hundreds of thousands displaced in election-related violence.”

Annan said Africa was not the sole subject of international justice, pointing out that criminal tribunals were first set up after the second world war, at Nuremberg and Tokyo. After the cold war, more international or mixed tribunals were launched for crimes in Lebanon, Cambodia and Yugoslavia. The ICC has opened investigations in Georgia and is conducting preliminary examinations in Afghanistan, Columbia, Ukraine, Iraq and Palestine.

He said the “ICC remains the continent’s most credible court of last resort for the most serious crimes … [It] does not supplant national jurisdictions; it only intervenes in cases where the country concerned is either unable or unwilling to try its own citizens.”