While this year will end with a record number of deportations from the United States, the focus of immigration enforcement is on people guilty of crimes, Homeland Security Secretary Janet Napolitano said Wednesday in a defense of the controversial Secure Communities program.

The S-COMM program has marked a change in the approach of Immigration and Customs Enforcement, she told an audience at American University in Washington.

"For the first time in decades, 50 percent of the aliens removed by ICE (in 2010) had been convicted of a criminal offense. In 2011, ICE will again remove a record number of convicted criminals from our country," the secretary said.

S-COMM was implemented by the Bush administration in March 2008 with the aim of boosting deportations of dangerous criminals and repeat violators of immigration law.

The program requires state and local law enforcement to share detainees' fingerprints with the FBI and the DHS, which checks them against its database of immigration offenders.

Civic and religious groups opposed to S-COMM cite official figures showing that roughly 200,000 undocumented immigrants without criminal records were deported during the 2010 fiscal year.

Predicting that deportations will set a new record in 2011, Napolitano said the total would "undoubtedly" prompt more complaints from S-COMM opponents.

"What those critics will ignore," she said, "is that while the overall number of individuals removed will exceed prior years, the composition of that number will have fundamentally changed. It will consist of more convicted criminals, recent border crossers, egregious immigration law violators and immigration fugitives than ever before."

The Homeland Security chief said S-COMM allows ICE to deal with the country's roughly 10 million undocumented immigrants as individuals.

"While all of these people are in our country unlawfully, their individual stories can differ dramatically. Some were brought here when they were children," Napolitano said. "They have spent almost their entire lives in the United States and have gone on to graduate from college or serve in our military."

"Others illegally crossed our borders for the purpose of committing crimes against our citizens," she added.

The secretary said DHS has made great strides in improving border security, though insisting that further progress is contingent on an overhaul of immigration law.

President Barack Obama says comprehensive immigration is a priority, but efforts to achieve it have run into opposition from most Republicans and even from some of the president's fellow Democrats.