David Steinman accused Tedros Adhanom Ghebreyesus, 55, who took over at the WHO three years ago, of being one of three officials in control of the Ethiopian security services from 2013 to 2015.

Dr Tedros was the country's health minister from 2005 to 2012 and its foreign minister until 2016, when his Tigray People's Liberation Front party was the main member of the ruling coalition.