NOGALES, Ariz. — Roman Catholic leaders made a rare visit to the border and celebrated Mass on Tuesday in the shadow of the fence separating the U.S. and Mexico, offering Holy Communion through the steel barrier to people on the Mexican side as they sought to bring attention to the plight of immigrants.

Cardinal Sean O'Malley, the leader of the Boston Archdiocese, led a delegation of bishops from around the country and Mexico in the trip to the border, less than a week after President Barack Obama discussed immigration reform in a meeting with Pope Francis. They toured the border city of Nogales, walked along a notorious section of the border that was once a popular crossing point for drug and immigrant smugglers, and celebrated Mass just a few feet from the fence.

People reach through the fence from the Mexican side of the border to celebrate communion.John Moore / Getty Images

The Catholic leaders believe that immigration is a humanitarian issue that deserves urgent attention by Congress. They cite the dozens of immigrants who die each year in the brutal desert terrain while trying to cross illegally into the United States along the roughly 2,000-mile-long border with Mexico and note that the immigrants are simply trying to find better lives in America.

"This is not just a political or economic problem," O'Malley said Tuesday. "This is a moral problem."

Several hundred people attended the Mass, which was translated into Spanish, and a few dozen people peered through the border fence from Mexico to watch the ceremony. O'Malley and Bishop Gerald Kicanas of the Tucson Diocese offered Holy Communion through the fence, providing people in Mexico wafers as a blessing as some of the recipients broke down in tears.

Tucson Diocese Bishop Gerald Kicanas offers Holy Communion through the border.SAMANTHA SAIS / Reuters

Arizona state Sen. Al Melvin, a Republican running for governor, said the clergy visit will do little to solve problems on the border. He said developing private-sector jobs in northern Mexico and securing the border to prevent drug and human trafficking are needed to bring stability to both sides of the international boundary.

"Frankly, and I am a Catholic, I think this is irresponsible of these bishops to be down there," Melvin said. "They are not bringing stability to the border. They are adding to the chaos of the border. And it's not helping to save lives. If anything, I believe it will contribute to more lives being lost. We need to secure the border to protect lives."

— The Associated Press

Cardinal Sean O'Malley of Boston walks in the Arizona desert to see the conditions faced by migrants.SAMANTHA SAIS / Reuters