WASHINGTON — Already under siege, the Internal Revenue Service was cited by a government watchdog for a $4.1 million training conference featuring luxury rooms and free drinks, even as conservative figures told Congress Tuesday they had been abused for years while seeking tax-exempt status.

A total of 132 IRS officials received room upgrades at the 2010 conference in Anaheim, Calif., according to the report being released by J. Russell George, the Treasury inspector general for tax administration.

One official stayed five nights in a room that regularly goes for $3,500 a night, George's report said, and another stayed four nights in a room that regularly goes for $1,499 a night. The agency paid a flat daily fee of $135 per hotel room, it said, but the upgrades were part of a package deal that added to the overall cost of the conference. Without the upgrades, the IRS could have negotiated a lower room rate, as required by agency procedures.