The disclosure that the two watchdogs are focusing on the Civil Rights Division marks an expansion to a new arena of the Justice Department of an ongoing investigation into whether politics played a role in the firing of nine US attorneys in 2006. The probe has widened to encompass allegations that the administration has used its control of the Justice Department to gain a partisan edge.

"This is to notify you that we have expanded the scope of our investigation to include allegations regarding improper political and other considerations in hiring decisions within the Department of Justice," wrote Inspector General Glenn Fine and Office of Professional Responsibility chief Marshall Jarrett , who are conducting a joint inquiry.

Under federal law, officials may not take political affiliation into account when hiring career professionals, permanent, non-partisan employees who stay on when an administration changes. But last week, a former aide to Attorney General Alberto Gonzales , Monica Goodling , told Congress that she had "crossed the line" by attempting to block liberal applicants from being hired as career assistant prosecutors and immigration judges.

Goodling, a key figure in the US attorney firings who resigned in April, was granted immunity from prosecution in exchange for her testimony. While it was known that Goodling's hiring practices were under investigation, the letter made clear for the first time that the internal probe has now been extended to hiring by other administration appointees as well.

"Among the issues that we intend to investigate are allegations regarding Monica Goodling's and others' actions in DOJ hiring and personnel decisions; allegations concerning hiring for the DOJ Honors Program and Summer Law Intern Program; and allegations concerning hiring practices in the DOJ Civil Rights Division," they wrote.

The offices did not disclose whom else they are investigating. Dean Boyd , a Justice spokesman, declined to comment on the probe's expansion.