Two doctors on Wednesday raised concerns about the government's latest measures on secondhand smoke, saying they could lead to the 2020 Olympic Games in Tokyo being held in an "extremely smoky environment."

The criticism comes a day after the government announced the thrust of planned revisions to a law on secondhand smoke, saying smoking would continue to be permitted in small bars and restaurants that put up warning signs for potential customers.

The health ministry gave no specifics, but major newspapers reported it is contemplating allowing smoking in establishments with floor space of 150 square meters (1,615 square feet) or less.