More than 500,000 foreign visitors remained in the United States last year for longer than their temporary visas permitted, and more than 480,000 of them are suspected to still be living inside the country illegally, according to a new report from the Department of Homeland Security.

While 98.83 percent of the 45 million visitors to the U.S. in 2015 abided by the terms of their admissions and left the country before their visas expired, 1.17 percent, or 527,127 individuals, are believed to have stayed in the country unlawfully. Of those overstayers, about 482,781 were thought to still be in the country at the end of last year.

The figures only include those who entered the U.S. for business or pleasure by sea or air under the Visa Waiver Program or B Visa, not those from other major visa programs such as the F-1 student visa, H-1B foreign worker visa, H-2B visa, L-1 visa or the J-1 exchange visa, according to The Washington Examiner.

"Nor does it include those who arrived through land ports, thus millions who came on border crossing cards are excluded," said Sen. Jeff Sessions, R-Ala., the chairman of the Subcommittee on Immigration and the National Interest, reports Breitbart. "And, because this report was only generated using biographic data, and not biometric data, the true number of overstays is likely much higher."

Session noted that thousands of foreigners who overstayed their visas are from areas with high terrorist activity, including 440 individuals from Syria, 681 from Iraq, 219 from Afghanistan, 219 from Yemen, 922 from Indonesia, 56 from Libya, 564 from Iran, 1,147 from Bangladesh and 1,435 from Pakistan.

"This long-awaited report from the Department of Homeland Security demonstrates that we are in the midst of a national immigration crisis," Sessions added. "Visa expiration dates have become optional. The administration does not believe that violating the terms of your visa should result in deportation. What we are witnessing is tantamount to an open border. Millions are free to come on temporary visas and no one is required to leave."