First lady Michelle Obama's trip to Spain in August 2010 cost the U.S. Air Force and the Secret Service at least $467,585, Judicial Watch reported Thursday based on documents provided by the government under the Freedom of Information Act.

That price tag will likely add more fuel to an attack by Mitt Romney, who has already gone after President Barack Obama and his family for "elaborate vacations." Alluding to travel to the president's home state of Hawaii as well as the Spain trip, Romney said last week that the Obamas' vacations were in part to blame for the scandal over excessive spending by the General Services Administration.

The White House has said that the Obamas paid their own way for the Spain trip, during which the first lady, along with daughter Sasha, traveled around the country and visited with the royal family. Officials told The New York Times in August 2010 that two friends and four of their daughters, along with two aides and two advance staff members, went on the trip. The friends paid for their own rooms, food and transportation, the officials said.

The Air Force denied a request by Judicial Watch to provide the exact number of civilians who took the trip.

Even though the Obamas picked up some of the immediate costs, the government, which determines how much protection the first lady needs, spent a considerable sum on the trip, according to the conservative watchdog's report. The total cost of the flights was about $199,300, and the Secret Service spent about $254,500 on the vacation.

White House Press Secretary Jay Carney declined to comment Thursday on the latest information, saying the administration "addressed this issue a long time ago."

Also on HuffPost: