Global coronavirus infections topped nine million on Monday as the World Health Organization warned that the pandemic was accelerating and Saudi Arabia said it would allow a "very limited" number of pilgrims to the hajj next month.

Tedros said the greatest threat facing the world was not the virus itself, which has now killed over 465,000 people and infected nine million, but "the lack of global solidarity and global leadership."

Brazil is the second worst-affected country behind the United States, where the number of deaths topped 120,000 on Monday and political infighting has prevented a unified policy.

Saudi Arabia announced it would allow a "very limited" number of pilgrims to its annual hajj ritual, which last year drew 2.5 million pilgrims from around the world.

Australians were warned on Monday to avoid travelling to Melbourne, as the second-biggest city tightened restrictions over fears of an upsurge in cases.