Thai authorities say they will distribute medicine to citizens traveling to Japan to protect against radiation from damaged nuclear power plants.
The government already warns against unnecessary travel to Japan.
Potassium iodide is taken to help block absorption of radioactive iodine. Supplies in Japan have become short, and panic buying has been reported as far away as North America.
The government's National News Bureau says more than 70 percent of package tour bookings to Japan for March to May have been canceled.