Former executives of the scandal-hit Jichiro labor union were aware it was allegedly evading tax by not declaring commission income from insurance companies in the 1990s, labor and investigative sources said Saturday.

Jichiro, Japan's largest labor union, representing local government workers, received a total of 11.3 billion yen in commission revenue from insurance agents over a seven-year period to 2000 but did not declare any of the income until 1999, the sources said.

In that year, the union reported commission income for the years 1997 and 1998 only, they said, adding that part of the commission income was used for off-the-books spending.