The head of the World Health Organisation has said an investigation is under way into reports alleging that the UN health agency’s top official in the Western Pacific engaged in racist, unethical and abusive behaviour.

It follows a report last week by the Associated Press (AP).

At a meeting of the WHO’s executive board over the weekend, Tedros Adhanom Ghebreyesus said the agency was first made aware of staff complaints about the reported misconduct of Dr Takeshi Kasai in late 2021.

“We take these allegations seriously and we have acted with urgency,” said Dr Tedros.

He said WHO headquarters was told of the claims in late 2021 and it was now “following due process with the co-operation of the staff member”, without specifying Dr Kasai.

Last week, the AP published an investigation that found WHO staff members alleged that Dr Kasai’s abusive, racist and unprofessional behaviour compromised the agency’s response to the Covid-19 pandemic.

Dr Kasai has denied the allegations.

The claims were laid out in an internal complaint filed in October and again in an email last week, sent by unidentified “concerned WHO staff” to senior leadership and the executive board and obtained by the AP.

Two of the authors said more than 30 staff members were involved in writing it, and that it reflected the experiences of more than 50 people.

The internal complaint and the email describe a “toxic atmosphere” with “a culture of systemic bullying and public ridiculing” at the WHO’s Western Pacific headquarters in Manila, led by Dr Kasai, director of a vast region that includes China and his home country of Japan.

The AP also obtained recorded snippets of meetings where Dr Kasai is heard making derogatory remarks about his staff based on nationality.

Eleven former or current WHO staff members who worked for Dr Kasai told the AP he frequently used racist language.

During Saturday’s closing session of the WHO’s executive board meeting, several countries pressured the organisation to investigate the allegations of misconduct reported by the AP.

Britain’s representative to the WHO called on the agency to “promptly investigate” the claims and said “we regret to have heard of this first in the media”, saying the WHO should have shared the information with its executive board as soon as it learned of the concerns.

The US said the reported racist and abusive behaviour “undermines the core values and essential lifesaving work of WHO and its regional offices around the world”.

Dr Tedros said because an investigation was now under way, he could not share more details about it.

Lawrence Gostin, of Georgetown University, called Dr Tedros “the moral conscience” of the pandemic.

“But the only way you can have credibility in your moral standing is if you’re leading an organisation which itself is behaving at the highest ethical standards, and too often that hasn’t been the case with WHO,” he said.

The WHO staff members who first reported the claims of abuse said they have not been informed of any investigation.

France’s diplomatic mission in Geneva last week said that if the reports prove to be true, the consequences could include Dr Tedros consulting with the executive board to have Dr Kasai’s contract terminated.