The comments follow those of Moderna chief executive Stephane Bancel, who last week in Tokyo said the company has held talks with the Chinese government about supplying vaccines but no decision has yet been made.

"We would certainly be very eager to collaborate with China if they felt that there was a need for a vaccine there," Burton told a media briefing to reporters in Asia. "Currently, there is no activity going on, but we'd be very open to it."

(Reporting by Rocky Swift, Editing by Louise Heavens)