Washington ? Teams assigned to make sure foreigners ordered out of the United States actually leave are grappling with a backlog of more than 600,000 cases and can’t accurately account for the fugitives’ whereabouts, the government reported Monday.

The report by the Homeland Security Department’s inspector general found that the effectiveness of teams assigned to find the fugitives was hampered by “insufficient detention capacity, limitations of an immigration database and inadequate working space.”

Even though more than $204 million was allocated for 52 fugitive operations teams since 2003, a backlog of 623,292 cases existed as of August of 2006, the report said.

The number of illegal immigrants in the United States has been estimated at between 11.5 million and 12 million. About 5.4 percent of them are believed to be “fugitive aliens,” those who have failed to leave the country after being ordered out.

Until the Sept. 11, 2001, terror attacks, attempts to catch such fugitives were mostly carried out by teams not exclusively devoted to the task. After the attacks, an Absconder Apprehension Initiative was created within the Justice Department to find, apprehend and deport such immigrants. When the Homeland Security Department was created in March 2003, it assumed responsibility.

Plans for the new office stated that it aimed to eliminate the case backlog by the end of 2012, although a field manual put the timetable at 2009, the report said.

Yet “despite the efforts of the teams, the backlog of fugitive alien cases has increased each fiscal year since the program was established in February 2002,” the inspector general said.