U.S. Rep. Tom Tancredo, R-Colo., said he has appeared on a dozen radio shows in the past week to talk about the "huge and growing problem" of illegal U.S. immigrants, The Washington Times reported.
U.S. Rep. Virgil Goode Jr., R-Va., also was outraged.
"I say if you are here illegally and are displaying and waving the Mexican flag, you should go back to Mexico and fly that flag there," Goode said.
Talkers Magazine Editor and Publisher Michael Harrison said immigration is the current No. 1 talk-radio issue.
"Many of the conservative hosts are against the waving of the Mexican flag (at rallies) and seeing such Mexican nationalism expressed in the United States," Harrison told The Times.
While it was reported that demonstrators waved only Mexican flags, Alvaro Huerta of the Coalition for Humane Immigrant Rights of Los Angeles said many also waved U.S. flags.