PROVIDENCE (AP) -- One of Rhode Island's top Hispanic lawmakers has asked Sen. Lincoln Chafee to denounce a television ad run by a Republican group supporting his bid for reelection because he said it could engender fear and prejudice against Hispanics.

The ad running on local broadcast and cable television accuses Cranston Mayor Stephen P. Laffey of being weak on national security because he has allowed the city to accept foreign identification cards presented by Mexican and Guatemalan immigrants.

Laffey is running against Chafee in the Sept. 12 Republican primary. Polls have shown it to be a very close race.

The National Republican Senatorial Committee, which backs Chafee, began running an ad last week that criticizes Laffey for Cranston's acceptance of matricula identification cards from Mexico. Laffey announced last year that the city would accept the identification cards Mexico and Guatemala issue to their citizens living abroad.

The NRSC ad shows images of Hispanic men being herded into van by a law-enforcement agent and says immigrants can use fake cards to get driver's licenses, enter government buildings and board planes.

State Sen. Juan Pichardo, D-Providence, sent Chafee a letter dated Friday asking him to renounce the spot.

"The ad's script and imagery are clearly meant to engender fear that, as a group, Hispanic immigrants present a threat to the security of Rhode Island and the nation," wrote Pichardo, a naturalized citizen who emigrated from the Dominican Republic. "I am deeply concerned that as a result, the ad will unfairly create feelings of prejudice and suspicion toward the Hispanic community as a whole."

Chafee described the ad as accurate during a Saturday night debate with Laffey.

But his spokesman Ian Lang referred questions to the NRSC after Pichardo's letter appeared yesterday on a Democratic Web site.

"This is not our ad, we have nothing to do with it," Lang said.

NRSC spokesman Dan Ronayne denied that the ad was anti-Hispanic in tone.

"This ad is about our national security, and it speaks to concerns raised by the FBI," he said.