WASHINGTON — The U.S. government has mistakenly granted citizenship to at least 858 immigrants from countries of concern to national security or with high rates of immigration fraud who had pending deportation orders, according to an internal Homeland Security audit released Monday.

The Homeland Security Department’s inspector general found that the immigrants used different names or birthdates to apply for citizenship with U.S. Citizenship and Immigration Services and such discrepancies weren’t caught because their fingerprints were missing from government databases.

The report does not identify any of the immigrants by name, but Inspector General John Roth’s auditors said they were all from “special interest countries” — those that present a national security concern for the United States — or neighboring countries with high rates of immigration fraud. The report did not identify those countries.

In an emailed statement, the Department of Homeland Security said the findings reflect what has long been a problem for immigration officials — old paper-based records containing fingerprint information that can’t be searched electronically. DHS says immigration officials are in the process of uploading these files and that officials will review “every file” identified as a case of possible fraud.