A small plane violated the restricted airspace around the presidential retreat of Camp David (search) while the president was spending the weekend there, federal authorities said.

The pilot was forced to land and was questioned but was released late Saturday without being charged, Secret Service (search) spokesman Jonathan Cherry said Sunday.

The White House did not respond to questions about whether President Bush had to be evacuated from the area during the incident or was even aware of the plane.

The small Cessna (search) was intercepted by two F-16 fighters about eight miles from Camp David at around 10:45 p.m. Saturday, Federal Aviation Administration spokeswoman Holly Baker told The Associated Press on Sunday.

The plane was forced to land at Frederick Municipal Airport.

The Frederick News-Post reported that a man and woman were questioned, but Cherry wouldn't comment on the report.

On Wednesday, the White House briefly went to red alert when another plane entered restricted airspace around Washington. President Bush was hurried from his residence to a safer location and lawmakers were ordered to evacuate the Capitol. Two fighters intercepted the twin-engine, propeller-driven plane eight miles northeast of the Capitol and escorted it to Winchester, Va.

On May 11, a Cessna violated restricted airspace and sent lawmakers and other government workers scrambling from the Capitol, the White House and other federal buildings. That plane also was escorted to Frederick.

Since Sept. 11, 2001, hundreds of pilots have violated Washington's restricted airspace. Private planes are not allowed to fly in the Air Defense Identification Zone, about 2,000 square miles radiating from the three airports around Washington, without a special transponder code and radio contact with the FAA. They're not allowed at all within 16 miles of the Washington Monument.