JOHANNESBURG (Reuters) - African leaders have rallied around the Ethiopian head of the World Health Organization (WHO) after U.S. President Donald Trump criticised the United Nations agency and threatened to withhold his country's contribution to its budget.

Trump had on Tuesday accused the WHO of being too focused on China and of issuing bad advice on the COVID-19 pandemic.

South African President Cyril Ramaphosa, who chairs the African Union (AU), said in a statement late on Wednesday that WHO Director General Tedros Adhanom Ghebreyesus had shown "exceptional leadership ... from the very earliest stages of this unprecedented global health crisis."

"The AU calls upon the international community to join hands to support the efforts of the DG and the entire WHO family as they lead global efforts to fight this pandemic," Ramaphosa added.

"If there was a time for global unity, solidarity and cooperation, this is that time."

Posting on Twitter, Rwanda's Paul Kagame said the WHO chief "has the full confidence and support of Africa," while AU Commission head Moussa Faki urged leaders to focus on fighting COVID-19 and said the time for accountability would come later.

Tedros, a former foreign minister of Ethiopia, has rejected Trump's suggestion that the WHO has been "China-centric" in its efforts to contain the spread of the new coronavirus.

"We are close to every nation, we are colour-blind," he said on Wednesday, adding the WHO had "kept the world informed about the latest data, information and evidence."

China has said Tedros had played an important role in promoting international cooperation to combat the pandemic, which has infected more than 1.47 million people and killed more than 87,000, according to the latest Reuters tally.

Africa accounts for a fraction of global cases of the disease, but its countries are feeling the impact with economies expected to contract, putting about 20 million jobs at risk.

"The window for containing the virus at the subnational and national level is closing in many countries," Tedros told diplomats in Geneva on Thursday. "The infection numbers in Africa are relatively small now, but they are growing fast."