* More people detained in immigration system than in federal prisons
* Think tank says data show border controls are working
The U.S. government spent nearly 24 percent more on federal immigration enforcement than on the FBI and all other main federal law enforcement agencies combined in fiscal 2012, a report showed on Monday.
The report by the Migration Policy Institute think tank said the federal government spent $18 billion in fiscal 2012 on Customs and Border Protection, Immigration and Customs Enforcement and the US VISIT program - Homeland Security's main immigration enforcement program that stores fingerprints and pictures of foreign visitors to the United States.
The combined total for other criminal law enforcement agencies including the FBI, Drug Enforcement Administration, Secret Service, U.S. Marshals Service and the Bureau of Alcohol, Tobacco, Firearms and Explosives was about $14.4 billion.
The 182-page report said more people are detained each year in the immigration system than are serving sentences in federal Bureau of Prisons facilities for all other federal crimes.
"Today immigration enforcement can be seen as the federal government's highest criminal law enforcement priority, judged on the basis of budget allocations, enforcement actions and case volumes," said MPI senior fellow Doris Meissner, who served as commissioner of the U.S. Immigration and Naturalization Service from 1993 to 2000.
The authors of the report says the data proves that stricter border controls - something supported by both Republicans and Democrats - have been set up and are working. They pointed to record high deportation levels and a 40-year low in apprehensions at the U.S.-Mexico border as examples.
But Meissner said enforcement alone is not enough, saying it was more a "precondition" for broader immigration policy reform.
After failing to revamp the immigration system in his first term President Barack Obama has vowed to introduce legislation this year to overhaul the country's "broken immigration system".
Immigration reform supporters believe the 11 million undocumented foreigners in the United States should be allowed a path to work toward citizenship. But opponents believe this would reward people who broke the law by coming to the United States illegally.