New York.– The U.S. government is spending more than $1.5 billion each year to jail illegal immigrants throughout the country, according to a new report by the investigative arm of Congress.

Over the past five fiscal years the number of incarcerated non-U.S. citizens in federal prisons has increased by 4,000, to about 55,000. In state prisons, the criminal alien population has increased by about 75,000 people, for a total of 296,000.

The report, issued this week by the Government Accountability Office (GAO), found that nearly 70 percent of the criminal aliens in federal prisons, and 66 percent in state prisons, were born in Mexico. About five percent are from the Dominican Republic, and five percent from Colombia.

The document reads that about 50 percent of the criminal aliens in the study population were arrested at least once for either assault, homicide, robbery, a sex offense, or kidnapping. About half of the criminal aliens were arrested at least once for a drug violation.