WASHINGTON — An independent inquiry into the attack on the US diplomatic mission in Libya that killed four Americans on Sept. 11 sharply criticizes the State Department for a lack of seasoned security personnel and relying on untested local militias to safeguard the compound, congressional and State Department officials said Tuesday night.

The investigation into the attacks on the mission and CIA annex that killed Ambassador J. Christopher Stevens and three others also faulted State Department officials in Washington for ignoring requests from officials at the US Embassy in Tripoli for more guards and safety upgrades for the diplomatic mission.