The World Health Organisation (WHO) is "unlikely" to list coronavirus as a disease that requires vaccination proof, a spokesperson has said.

The comment comes after the Morrison government said that international travellers entering Australia will likely need proof they have been vaccinated for COVID-19 or face 14 days in hotel quarantine on their own.

Dr Margaret Harris from WHO told Today it would be difficult to make the vaccine mandatory.

"That would be unlikely. I think it would be a long way off from us listing that," Dr Harris said.

"If that happened, that would be an external review group that would do that as part of the international health regulations.

"That would take basically the countries involved in setting up that treaty to make that decision. In other words, that's a very theoretical and quite sort of distant concept."

Dr Harris said that Prime Minister Scott Morrison can enforce the "no jab, no flight rule" without the approval of the World Health Organisation.

"He can do that," she said.

"Those decisions are all national decisions. We make overall recommendations. Generally most countries do follow them. But it is up to the national authorities to decide what regimes, what vaccines they want people to have had and where."

They've said if it goes ahead, WHO can't enforce the matter.

"It is not that we wouldn't necessarily support it," she said.

"What I am saying is we would not necessarily make it (a vaccine) mandatory. That would be a decision for all the countries of the world to make. We as WHO, we are the advisers. We are not the police."