U.S. Customs and Border Patrol agents made fewer arrests of illegal immigrants trying to enter the country last year, the government said Monday in a report that credits stronger enforcement.

Arrests fell 8.4 percent from 1.2 million in fiscal year 2005 to 1.1 million last year. It was the first decrease since 2003, the Homeland Security Department said in releasing its annual statistics on illegal immigration.

"What we ideally would like to do is stop them from coming in the first place. The extent that we see fewer crossing the border, that suggests that line of defense is working," Homeland Security Secretary Michael Chertoff said in a news briefing.

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He noted that the department added more than 1,900 border patrol agents in the last year and installed fencing and other security measures such as electronic sensors and cameras.

"These kinds of successes underscore the importance of viewing what we do to protect our borders as part of a comprehensive solution, one that allows us to target the worst of the worst," Chertoff said.

Monitor the disorder on the border at FOXNews.com's Immigration Center.

Statistics released Monday also show the government:

—Removed a record 186,600 illegal immigrants from the United States in the past year. That's a 10 percent increase from 2005.

—Seized more than 1.3 million pounds of marijuana, a 13 percent increase from the previous year.

—Nearly tripled the number of fugitive operations teams, from 18 to 50, as part of efforts to locate, apprehend and remove criminal aliens.

The figures, which were complete a month ago, were released a week after President Bush signed a bill authorizing 700 miles of new fencing along the U.S.-Mexico border.

The new law, which didn't come up with new funding beyond the $1.2 billion previously approved by Congress, gives Republican candidates a pre-election platform for asserting they're tough on illegal immigration. Congressional elections are Nov. 7.

On Monday, Chertoff said improved border security will not be enough. The centerpiece of Bush's immigration policy, a guest worker program, remains stalled in Congress.

"Without a temporary worker program, getting control of the border by the end of 2008 would be very, very difficult," Chertoff said.

Visit FOXNews.com's Immigration Center for complete coverage.