Deputy Inspector General Anne Patterson made the remarks testifying before the immigration subcommittee of the House Judiciary Committee, saying new fraud protections are insufficient, the Washington Times said Friday.
"The bottom line is it's a program that can be taken advantage of by hostile intelligence officers or terrorists," said Patterson.
Her opinion was echoed by Rep. Robert W. Goodlatte, R-Va., who is sponsoring a bill to end the diversity lottery.
"This program remains a serious security threat," Goodlatte said.
The lottery's goal is to broaden the nation's pool of immigrants, and millions of people apply each year, from which about 110,000 names were selected in the 2004 lottery.
Those selected then must apply and go through the visa process. In the end, 50,000 green cards are issued.
Citizens from some countries who already have a high rate of immigration to the United States are excluded from the lottery. They include Canada, Mexico, Haiti, Great Britain, Russia, mainland China, India, Pakistan, South Korea, Vietnam and the Philippines.