Scott Morrison has defended the use of a $4305-an-hour taxpayer-funded jet to assist former senator Mathias Cormann's push to become the next head of the OECD, saying the risk of him catching COVID-19 is extremely high.

Mr Cormann has also been assigned a staff of about eight bureaucrats to assist with the campaign, prompting Labor to demand the Prime Minister reveal how much money had been allocated to the bid.