WASHINGTON – Hundreds of available trucks, boats, planes and federal officers were unused in search and rescue efforts immediately after Hurricane Katrina hit because FEMA failed to give them missions, new documents show.

Additionally, the Federal Emergency Management Agency called off its search and rescue operations in Louisiana three days after the Aug. 29 storm because of security issues, according to an internal FEMA e-mail given to Senate investigators.

The documents, released by the Senate Homeland Security and Governmental Affairs Committee, are further evidence of lapses in FEMA’s response to Katrina. They also detail breakdowns in carrying out the National Response Plan, which was issued a year ago specifically to coordinate response efforts during disasters.

Sen. Susan Collins, R-Maine, head of the Senate committee that released the documents, called them “the most candid assessment that we’ve received from any federal agency.” Her panel, which is investigating the government’s response to Katrina, is scheduled to question a FEMA operations official Monday at a hearing focusing on search and rescue efforts.