UN High Commissioner for Human Rights Michelle Bachelet, whose term ends Wednesday, will be temporarily replaced by her deputy until her successor is named, the UN secretary-general's spokesperson said Tuesday.

"Tomorrow is Michelle Bachelet's last day. I don't expect an announcement tomorrow" on her successor, Stephane Dujarric told a press briefing.

Until the appointment of a replacement, as "of the first of September, Nada Youssef Al Nashif, who is a deputy High Commissioner for Human Rights, will be the officer in charge," he added.

Asked about a possible date for UN chief Antonio Guterres to announce his nomination for the sensitive post, Dujarric said he could not "predict what will be happening."

"We're trying to do this as quickly as possible, as diligently as possible," he said.

The person chosen by Guterres will then have to be confirmed by the UN General Assembly.

Bachelet took office on September 1, 2018, and announced in June that she would not seek a second term in order to spend time with her family and in her own country.

The former Chilean president has been severely criticized in recent months by the United States and also by major NGOs, who accuse her of a lack of firmness in the face of human rights violations in China. Some have accused her of behaving as a "diplomat" rather than as a defender of human rights.

In an open letter to the UN Secretary General, more than 60 NGOs called in June for a new human rights chief with "courage" in the face of the most powerful countries.

"This is not a job for a nice, quiet diplomat, because a quiet diplomat has no leverage. Nobody listens to a quiet diplomat. Nobody changes their behavior because of a quiet diplomat," Kenneth Roth, the outgoing head of Human Rights Watch, said in a recent interview with AFP.