The pay of an individual in arrears to the United States shall be withheld until he has accounted for and paid into the Treasury of the United States all sums for which he is liable.

When pay is withheld under subsection (a) of this section, the employing agency, on request of the individual, his agent, or his attorney, shall report immediately to the Attorney General the balance due; and the Attorney General, within 60 days, shall order suit to be commenced against the individual.