SAN DIEGO -- Republican presidential candidate Mitt Romney toured the U.S.-Mexican border Monday and then repeated his call for tighter border security and decried cities that are self-declared sanctuaries for illegal immigrants.

"It sends a signal to people on the other side of the border and around the world, not just here in Mexico, but around the world, that hey if you can get into the United States we'll take care of you and we're not going to enforce the law," Romney told reporters in San Ysidro. "That is simply wrong."

Romney has extensively discussed illegal immigration recently, including accusing Republican front-runner Rudy Giuliani last week of instructing New York City workers not to provide information to the federal government that would help in find illegal immigrants when he was mayor from 1994-2001.

A Giuliani campaign spokeswoman said "Mitt Romney is as wrong about Mayor Giuliani's position on illegal immigration as he was when he last mischaracterized the mayor's record and later had to apologize."

"New York is the safest large city in America since Mayor Giuliani turned it around -- it is not a heaven for illegality of any kind," Katie Levinson said. "The mayor's record speaks for itself."

On Monday, the Giuliani campaign announced its immigration policy advisers, including former U.S. Customs and Border Protection Commissioner Robert Bonner. The campaign also distributed to reporters a set of comments by Giuliani, dating back to 1981, calling for securing the borders and deporting illegal immigrants.

Romney, a former Massachusetts governor began his day meeting voters at a Fresno bakery, before heading to San Diego. He will end his day with a fund-raiser in Irvine.

Romney's visit came three days after he praised the Bush administration's newly announced efforts to improve border security, worksite enforcement and help immigrants assimilate into American culture.

The administration pledged to increase the number of Border Patrol agents, strengthen efforts to keep international gang members out of the country and expand measures to identify people who have overstayed their visas.

The plan also calls for training local law enforcement officers to address illegal immigration; increasing fines on employers who knowingly hire illegal immigrants; and starting a Web site to help immigrants learn English.

The "stepped-up measures to enforce existing immigration law is a welcome development," Romney said Friday. "We must get serious if we are to secure our nation's borders.

"For far too long, lax enforcement and the adoption of policies that have created sanctuary cities for those entering the country illegally have put a strain on our border enforcement efforts and worsened our illegal immigration problem. We must take action to prevent sanctuary city policies that invite more illegal immigration and offer zones of protection for lawbreakers."

Rep. Zoe Lofgren, D-San Jose, the chair of the House Judiciary Subcommittee on Immigration, Citizenship, Refugees, Border Security and International Law, said she is "skeptical that this administration can deliver on its promises."

"The administration finally recognizes that it has failed in its duties to administer the immigration laws," Lofgren said. "We shall see whether a dysfunctional agency that deports an American citizen and cannot keep count of the number of visas issued can effectively implement these proposals."

Rep. Duncan Hunter, R-El Cajon, who is also running for the Republican presidential nomination, was scheduled to speak Monday night at a meeting of the Republican Party of San Diego County.