By Bruce Olson

ST. LOUIS (Reuters) - Controversial conservative radio talk show host Rush Limbaugh was quietly inducted into a hall of famous Missouri natives on Monday in a ceremony held under tight security at the State Capitol in Jefferson City, a legislative spokesman said.

A bust of Limbaugh, who is known for his scathing attacks on President Barack Obama and other Democrats, will join an exclusive group including writer Mark Twain and former president Harry Truman in the Hall of Famous Missourians.

Missouri Republican House Speaker Steve Tilley said Limbaugh was honored because he was the "voice of conservative America for more than a decade."

Democrats said the award was inappropriate because of his history of his partisan history and penchant for personally attacking those he disagrees with.

"That this was done without the general public, shows what an embarrassment it is," said Missouri House of Representatives Minority Leader Mike Talboy.

Tilley did not announce the date of the induction and the private, invitation-only ceremony was attended by about 100 state Republicans and a few other invitees, House spokesman Trevor Fox said.

Missouri State troopers guarded the doors to the chamber during the event. There were no incidents at the ceremony, the spokesman said.

"I'm stunned. Not speechless, but close to it, quite unable to comprehend this. This is something I never, ever considered would happen to me," Limbaugh said, according to an audio tape of his remarks played to Reuters by Fox.

Limbaugh had to apologize in March for referring to a Georgetown University law student who advocated access to contraceptives at a Congressional hearing as a "slut" who "wants to be paid to have sex." The incident lost him some advertisers.

Tilley shares a southwest Missouri background with Limbaugh, who was born in Cape Girardeau, Missouri.

Others honored in the Hall where the Limbaugh bust will sit include baseball great Stan Musial, ragtime composer Scott Joplin and Native American guide Sacajawea.

Limbaugh's radio show is broadcast on more than 600 radio stations nationwide, according to his website.

(Editing by Greg McCune)