Mexico has agreed to take part in a program beginning July 12 that will provide free flights home for illegal Mexican immigrants arrested in the Arizona desert, U.S. officials said Tuesday.

Officials hope the program will both reduce deaths in the Southwestern desert and the attempts by illegal immigrants to enter the United States.

Mexico agreed in mid-June to the program announced this month by the Homeland Security Department (search).

Under the agreement, the voluntary "repatriation" plan would end no later than Sept. 30, the agency said Tuesday.

Asa Hutchinson (search), the Homeland Security Department's undersecretary for border and transportation security, said the program would save lives "by safely returning Mexican nationals to their homes, away from the dangers of the Arizona-Sonora desert where smugglers and the harsh summer climate contribute to the deaths and injuries of illegal border crossers."

In the fiscal year that ended last Sept. 30, 154 immigrants died in the Arizona desert.

Increased enforcement on other parts of the border have shifted illegal immigrant smuggling operations to Arizona. Some immigrants who are apprehended and deported at the border reconnect with smugglers there and make multiple attempts until they are successful.

The agreement allows illegal immigrants arrested in Arizona's Sonora desert region to volunteer to be returned home via charter airplane from Tucson, Ariz., to Mexico City or Guadalajara (search). The immigrants then will be returned by bus to their hometowns. Immigrants who live in northern Mexico will be given other options.

William Strassberger, Homeland Security Department spokesman, said the program's estimated cost is $12 million to $13 million, which will be paid by the United States. He said many immigrants will want to return home because of the harshness of their journey and exposure to the desert.

"Many of them have spent several days crossing a desert with blast furnace temperatures, struggling to get through," Strassberger said.

Mexico's Interior Ministry called the program "part of the humanitarian efforts by Mexico and the United States to aid and protect migrants who traverse high-risk zones, to prevent deaths and avoid abuses by migrant traffickers."

The program includes "full respect for the human rights" of migrants, the ministry said in a press release Tuesday.

Colorado Rep. Tom Tancredo, a supporter of tougher border enforcement, said he supports the effort, but he expects few people to volunteer for the program because they won't want to be so far from the border.

"You have to ask yourself how many of these folks will be willing to start the (journey) over again. ... If they go into the interior, they're going to have to pay another coyote," said Tancredo, a Republican. People who smuggle humans across the border are known as "coyotes."

The lateral repatriation program last year moved 6,000 Mexicans from Arizona to the Texas border cities. Mayors of those cities balked, saying the government was shifting Arizona's problem their way. Mayors of the cities on the Mexican side complained that the migrants were dumped, often without money for food or a bus ticket home.

The countries agreed to the following:

—Mexicans will be returned home in a safe, humane and dignified manner. Homeland Security officers will not handcuff or restrain Mexicans unless warranted in individual cases. Those charged with a crime, excluding illegal entry, are ineligible.

—The program is only available to Mexicans.

—Migrants who tell immigration officials they want to be returned to Mexico will be referred to the Mexican consul. Mexico plans to increase its consul staff in Arizona.

—The Mexican consul will interview the migrants and confirm they have asked to be returned to Mexico's interior.

—Those who decline will be deported by way of a port of entry on the U.S.-Mexican border.