WASHINGTON (Reuters) -- The US State Department said Wednesday that its head of diplomatic security had resigned and three other officials were relieved of their duties following a scathing official inquiry into the Sept. 11 attack on the US mission in Benghazi, Libya.

Eric Boswell, the head of the department's bureau of diplomatic security, has resigned immediately, State Department spokeswoman Victoria Nuland said in a brief written statement, adding that he, and the three unnamed officials who were relieved of their duties, were all put on administrative leave.