The US attorney general, Loretta Lynch, said it was “something that we are looking into”. The US Secret Service, responsible for the first lady’s safety, also expressed concern.
"The Secret Service is concerned any time unauthorised information that might pertain to one of the individuals we protect, or our operations, is allegedly disclosed," said communications director Cathy Milhoan.
The scan appears to have come from the breached personal Gmail account of a low-level part-time contractor at the White House hired to aid in travel logistics.
Confidential information including travel details, names, social security numbers and birth dates of members of staff were also published online.
The documents were posted on DCLeaks.com, the same site on which emails from former Secretary of State Colin Powell appeared last week.