(CNN) During an overseas trip in 2015, Rear Adm. Ronny Jackson, the White House physician, was intoxicated and banged on the hotel room door of a female employee, according to four sources familiar with the allegation.
The incident became so noisy, one source familiar with the allegation told CNN, that the Secret Service stopped him out of concern that he would wake then-President Barack Obama.
Two sources who previously worked in the White House Medical Unit described the same incident, with one former staffer telling CNN that it was "definitely inappropriate, in the middle of the night," and that it made the woman uncomfortable.
At the time, the incident was reported up the chain of command, and it is one of multiple drunken episodes involving Jackson on overseas trips, according to a source familiar.
Members of the Senate Veterans' Affairs Committee have been working through all of the allegations, but have not substantiated the claims, with little documentation available to corroborate them.
The White House did not respond to requests for comment. After this story was published, the Secret Service released a statement saying that it had no record of "any incident, specifically, any incident involving Rear Admiral Ronny Jackson."
"A thorough review of internal documents related to all Presidential foreign travel that occurred in 2015, in addition to interviews of personnel who were present during foreign travel that occurred during the same time frame, has resulted in no information that would indicate the allegation is accurate."
The incident is the most detailed account so far of allegations that have emerged, causing concerns about Jackson's nomination to serve as the veterans affairs secretary. Senate Veterans' Affairs Committee members are assessing allegations from whistleblowers who have told the panel about Jackson's questionable behavior including excessive drinking and a "toxic" work environment under his leadership, according to two former White House medical staff members who have spoken with the committee.
Montana Sen. Jon Tester, the top Democrat on the Senate Veterans' Affairs Committee, told CNN earlier Tuesday that his committee had spoken with 20 former and current members of the military about Jackson, and that the allegations brought to the committee included concerns about his use of alcohol while on the job.
"If you are drunk and something happens with the president, it's very difficult to go in and treat the president," Tester said in an interview with CNN's Anderson Cooper. "That's what multiple people told us this was the case on several different trips."
Sen. Jerry Moran, a Kansas Republican who met with Jackson Tuesday, said that the nominee had denied the allegations against him, including drinking on the job.
"He does deny that he's done anything wrong in his service to the country. And particularly his time at the White House as a physician in the medical unit," Moran said. "He indicated that he knows of nothing that would prohibit him from being qualified, capable and the right person to the secretary of the Department of Veterans Affairs."
Asked about allegations of Jackson's drinking while on official travel, one former White House Medical Unit staffer told CNN that it raised questions about his judgment.
"You're 24 hours on call," the source said. "At night if you're the physician to the President and you're on a trip, you shouldn't be drinking," the source said.
UPDATE: This story was updated to include a statement from the Secret Service released after publication.