Japan has begun surveying overseas arrivals about their COVID-19 vaccination status as it explores the feasibility of exempting those vaccinated abroad from the country's strict entry restrictions, government sources said Tuesday.

While Japan has decided to issue so-called vaccine passports to enable residents who have been fully inoculated against the coronavirus to travel internationally, it has yet to ease border measures for holders of such vaccine certificates issued abroad.

But with more than 10 different vaccines used around the world, a number of issues remain to be resolved, including whether those not approved by the government will be recognized.