WASHINGTON — The inspector general for the General Services Administration said Monday that he is investigating possible bribery and kickbacks in the agency, as lawmakers assailed the former GSA administrator for allowing a Las Vegas spending scandal to erode taxpayers’ trust in government.

Inspector General Brian Miller told a congressional committee scrutinizing an $823,000 Las Vegas conference that his office has asked the Justice Department to investigate “all sorts of improprieties” surrounding the 2010 event, “including bribes, including possible kickbacks.”

Miller’s revelations of possible further misconduct by organizers of the four-day event enraged Democrats and Republicans on the House Oversight and Government Reform Committee. During a tense four-hour hearing, lawmakers scolded former administrator Martha N. Johnson and her colleagues.

Taxpayers picked up the tab for a mind reader, bicycles for a team-building exercise and a slew of private parties at the conference.

Johnson, speaking publicly for the first time since her resignation last week, called the Western Regions Conference a “raucous, extravagant, arrogant, self-congratulatory event that ultimately belittled federal workers.” She said, “I will mourn for the rest of my life the loss of my appointment.”