The Japanese Environment Minister says the government will start investigating the effects of mercury on human health within two years.
Environment Minister Ito Shintaro made the announcement at a meeting with sufferers of Minamata disease, which is caused by mercury poisoning, on Monday.
The meeting was held in Minamata City in the southwestern Japanese prefecture of Kumamoto, where the name of the disease comes from.
Six groups, including those representing Minamata disease sufferers, took part.
Ito said the government will use an investigation method that it claims is an objective way to assess the health effects of mercury.
The groups argue that the government's way of conducting tests on individuals takes too long.
They have been urging the government to swiftly conduct an effective investigation that takes advantage of the results of past tests.
They have also been asking the government to conduct a questionnaire surveying everyone living on the coast of the Shiranui Sea where Minamata disease was reported.
In response, Ito said the government will consider a proposed method by the groups and further study the matter from a broad perspective.
Some participants said they are concerned the planned investigation may not cover all residents on the coast and therefore will not reveal the entire extent of health damage.
Others were demanding a firm deadline for the investigation.
Monday's meeting was a follow-up of a previous meeting with the groups in which a ministry official cut the microphones of participants while they were speaking. Ito later apologized.
The minister will come back to Minamata City on Wednesday to sit down and talk with one group after briefly returning to Tokyo for other official business.
On Thursday, he is due to visit an island in the area of water where Minamata disease has been reported and have discussions with another group.