TOKYO, Sept 1 (Reuters) - Japan's health ministry said on Tuesday it planned to participate in the World Health Organization's COVID-19 vaccine programme known as COVAX.

A ministry official told reporters Japan would join COVAX, which had an Aug. 31 deadline for countries to express interest. The decision is non-binding, the official said, and financial contributions would be decided ahead of a Sept. 18 deadline.

The COVAX programme, launched in late April, is designed to serve as an insurance policy to secure access to COVID-19 vaccines. Participation has been uncertain as several wealthier nations, including Japan and the United States, have struck their own deals for vaccines.

Through overseas deals and domestic production, Japan is on track to have more than 500 million doses of six different COVID-19 vaccines by next year for its population of 126 million. (Reporting by Rocky Swift; Editing by Tom Hogue)