World leaders pledged on Friday to accelerate work on tests, drugs and vaccines against COVID-19 and to share them around the globe, but the United States did not take part in the launch of the World Health Organization (WHO) initiative.

French President Emmanuel Macron, German Chancellor Angela Merkel and South African President Cyril Ramaphosa were among those who joined a video conference to launch what the WHO billed as a "landmark collaboration" to fight the pandemic.

The aim is to speed development of safe and effective drugs, tests and vaccines to prevent, diagnose and treat COVID-19, the lung disease caused be the novel coronavirus - and ensure equal access to treatments for rich and poor.