The United States has revoked the entry visa of the prosecutor of the International Criminal Court, Fatou Bensouda, her office said on Thursday, a response to her inquiry into possible war crimes by US forces in Afghanistan.

Secretary of State Mike Pompeo said last month the US would withdraw or deny visas to ICC staff investigating such allegations against US forces or their allies.

United Nations human rights experts called the reaction “improper interference” in the work of the world’s permanent war crimes court. It also drew criticism from within the European Union.

“We can confirm that the US authorities have revoked the prosecutor’s visa for entry into the US,” Bensouda’s office told Reuters in an e-mail.

It said it understood the move should not impact Bensouda’s travel to the US to meet her United Nations obligations.

The ICC is not a UN court, but Bensouda travels regularly to brief the UN Security Council on cases referred to The Hague by the UN body.

A State Department spokesman said members of international organisations planning official travel to the UN could apply for diplomatic visas. “We recommend that applicants apply as early as possible to maximise the chances of being found eligible,” the spokesman said.

The US is not a member of the ICC, along with other major powers Russia and China.

The office of the prosecutor said on Thursday that Bensouda would exercise her duties “without fear or favour”.

She has been investigating alleged war crimes by all parties in the conflict in Afghanistan since November 2017, including the possible role of US personnel in relation to the detention of suspects.

ICC judges are still reviewing materials and have not yet handed down a decision on opening a formal investigation in Afghanistan.

The ICC is a court of last resort with 122 member states. It acts only when countries within its jurisdiction are found to be unable or unwilling to seriously investigate war crimes, genocide or other serious atrocities.

- Reuters