The United States says it has arrested 2,900 illegal immigrants — all with prior criminal convictions — during a seven-day sweep across the country.

U.S. Immigration and Customs Enforcement said Wednesday the operation was the largest of its kind, leading to arrests in all 50 U.S. states and in four U.S. territories.

The arrests come one month after Homeland Security Secretary Janet Napolitano said a new focus would be put on deporting criminals and serious violators of immigration law.

But a federal judge Wednesday ruled to allow Alabama to enforce large portions of a stringent state law against illegal immigrants. It includes one statute that requires public schools to check whether students are legal residents, and another that allows police to verify the status of anyone they suspect of being in the country illegally.

However, the judge blocked some portions of the law, including the parts that would make it a crime for illegal immigrants to seek work and for anyone to drive or house an illegal immigrant. Also blocked was the section that would allow people to sue companies for firing a legal worker while hiring ones without proper documents.

A coalition of civil rights groups had filed a class action lawsuit against the measure, saying it invited racial profiling and would target for harassment anyone who looks “foreign.”

The Justice Department also argued against the law, saying immigration laws and enforcement are the responsibility of the federal government.

More than 1,200 of the illegal immigrants arrested in last week's federal operation had multiple convictions, while more than 1,600 had convictions including manslaughter, attempted murder, kidnapping, sexual crimes against minors, drug trafficking and armed robbery.

The ICE-led operation, dubbed “Cross Check,” follows several similar operations that have resulted in the arrest of more 4,500 convicted illegal immigrants since 2009.

With an estimated 11 million undocumented immigrants living in the U.S., ICE Director John Morton said the operation underscores the Obama's administration's commitment to the arrest and removal of illegal immigrants with criminal convictions.

Meanwhile, a top ICE official in Southern Florida has been arrested on child pornography charges. Anthony Mangione could face up to 20 years in jail for transporting, receiving, and possessing sexually explicit images of minors. The 50-year-old pleaded not guilty in court on Wednesday.