The Japan Pension Service is reviewing its assignment of the same four digits to the pension numbers of individuals with gender identity disorder who changed their gender designation.

"The Japan Pension Service is looking to see if it is possible not to give them the specific numbers, to respect their privacy," Nobuyuki Takakura, head of pension management at the Health, Labor and Welfare Ministry, said Thursday.

Responding to a question in a Diet session, Takakura added, "The pension service still needs to ensure accurate data management."

The pension service has been assigning since last October the same first four digits to the 10-digit basic pension numbers of individuals who have changed their gender designation, the ministry said.

The new system has been criticized by people with GID and their supporters as a violation of privacy, as employers can learn of changes in gender designation.