Thailand's public health ministry said Wednesday that it would hand out free iodine tablets to passengers at airports where jets are departing for disaster-stricken Japan.

Fears about harmful nuclear contamination are growing after a series of explosions, fires and radiation leaks at a nuclear facility on Japan's northeastern coast, following Friday's massive earthquake and tsunami.

"I have already ordered the government pharmaceutical organisation to produce back-up iodine tablets for special purposes," said a ministry statement.

"Initially, we will produce 15,000 tablets to distribute for free at the airports which have flights from Thailand to Japan, such as Suvarnabhumi airport (in Bangkok) and Phuket airport, starting tomorrow," it said.

"But we will screen and give only to passengers who are travelling to the risk area in northern Japan."

The ministry warned against all but necessary travel to the area, also saying it would offer advice and screenings to those returning to Thailand from Japan.