U.S. issues an alert about rail security, days after bin Laden raid

New York (CNN) - The U.S. Department of Homeland Security released a notice tied to rail security Thursday, an alert that a law enforcement source said was tied to information taken from Osama bin Laden's compound in Pakistan.

The notice says that, in February 2010, al Qaeda members discussed a plan to derail trains in the United States by placing obstructions on tracks, according to a source who received the notice.

The plan was to be executed this fall, on the 10th anniversary of the September 11, 2001, attacks. But no specific city or rail system was identified in the notice, the source said.

The federal department confirmed the notice to federal, state, local and tribal authorities, with spokesman Matt Chandler stressing that "this alleged al Qaeda plotting is based on initial reporting, which is often misleading or inaccurate and subject to change."

"We have no information of any imminent terrorist threat to the U.S. rail sector, but wanted to make our partners aware of the alleged plotting; it is unclear if any further planning has been conducted since February of last year," Chandler said.

This development came days after U.S. commandos flew into an Abbottabad housing compound, killed bin Laden and four others, then took off with his body and numerous materials.