WASHINGTON, March 18 (Reuters) - The Bush administration freed up $175 million on Monday to help more than 300 U.S. airports offset security costs incurred since Sept. 11. The money came from Defense Department accounts and will help airports pay for extra law enforcement personnel, airport surveillance, and programs to review and reissue security credentials to employees, Department of Transportation officials said. In reviewing applications for government aid, the Federal Aviation Administration found that the cost of tighter security hit smaller airports hard. More than 184 small airports will be reimbursed for 100 percent of their extra security costs since the hijacked airline attacks on New York and Washington. But most of the money will go to medium and large airports, which will get back about 60 percent of what they spent for added security. ©2002 Reuters Limited.