WASHINGTON — The Senate Ethics Committee admonished Republican Sen. Pete Domenici on Thursday for creating an "appearance of impropriety" after he called the U.S. attorney he helped install to inquire about the timing of a federal corruption case.

However, the committee said that it had found no "substantial evidence" that the New Mexico senator attempted to improperly influence the investigation into Democrats.

U.S. Attorney David Iglesias of New Mexico accused Domenici of calling him in mid-October 2006 to pressure him to rush the investigation before the November elections to benefit Republicans.

Iglesias, who was fired in December 2006, alleged that he was fired because he didn't speed up the case.

After McClatchy reported on the phone call, Domenici apologized, but denied trying to improperly influence the probe.

Iglesias' allegations helped sparked a more than yearlong congressional investigation into the firings of nine U.S. attorneys, including Iglesias. An investigation by the Justice Department's inspector general is ongoing.

Domenici said in a statement Thursday that he was "gratified" that the committee decided not to launch a formal review.

"Nevertheless, as I said publicly last March when this complaint was originally filed, I regret the distraction this controversy has caused my colleagues, my staff, my family and, most importantly, my constituents," he said.

In October, Domenici, first elected in 1972, announced he would be retiring at the end of his term because of health reasons.

Iglesias said the committee's findings had "revived his confidence in the rule of law." He said he believed the admonishment would serve as a warning to other members of Congress that contacting federal prosecutors in such a way is "impermissible and unacceptable behavior."