Russia is ready to provide up to 300 million doses of its Sputnik V vaccine to the UN-backed Covax initiative, a top Russian official promoting the shot says, even though the World Health Organisation (WHO) hasn't yet signed off on it and production issues have fanned customers' concerns worldwide, reports AP.

Russian Direct Investment Fund CEO Kirill Dmitriev and the WHO have vastly different takes on when the Russian vaccine would get the WHO's stamp of approval.

Sputnik V has been authorised for use in 70 countries around the world despite not yet being approved by the UN health agency even for emergency use.

Dmitriev told AP that the Russian vaccine will be made available to Covax once the shot is approved by the WHO. He said he expects WHO's approval to come in the next two months.