The government concluded Friday that four companies had used foreign trainees to perform work cleaning up radioactive contamination after the March 2011 tsunami triggered meltdowns at the Fukushima No. 1 nuclear plant.

The headline figure from the final report on a survey conducted by the Justice Ministry, the labor ministry and the Organization for Technical Intern Training was the same as that in the interim report, released in mid-July, which reflected results of surveying fewer than 200 companies with foreign trainee programs.

Officials visited a total of 1,018 such companies with facilities in eight prefectures in eastern and northeastern Japan, interviewing technical interns there to confirm the situation, after the issue came to light in March.