One in 10 US secret service agents are aware of colleagues who have drunk excessively to the point they are "a security concern", according to an internal survey of elite personnel whose responsibilities include protecting the president.



Findings in the survey, buried in a recently released inspector general report, raise serious questions about the conduct of secret service agents, one of whom was found highly intoxicated at a hotel in the Netherlands on Sunday, hours before the arrival of Barack Obama this week.



The agent, and two others considered complicit in the incident, have been sent home for "disciplinary reasons", in the latest controversy involving agents engaging in questionable conduct abroad.



The Washington Post, which first reported the incident, said the agent was found drunk and passed out in a hallway in the Huis Ter Duin hotel on Sunday morning. It was the same hotel, a short drive from The Hague, where Obama stayed on Monday night on the first leg of a tour of Europe and the Middle East.

The Post said all three agents were on the counter-assault team, an elite unit that defends the president if he comes under attack, and that one agent was a team leader.

"We didn't have three guys crazy partying," an official with knowledge of the incident told the Guardian. "It was one guy who had too much to drink. Two guys apparently didn't take care of their buddy."



The official, who spoke on the condition of anonymity, said there was no evidence that marijuana was also used by the agent, and was unable to say whether the trio had been placed on administrative leave pending the disciplinary investigation that is now under way.



The White House has not formally commented on the incident, which puts another dent in the reputation of the secret service, whose director, Julia Pierson, is personally accompanying Obama on Air Force One.



The inspector general's inquiry, commissioned after 13 agents were suspected of drinking and soliciting prostitutes in Cartagena, Colombia before a visit by Obama in 2012, largely exonerated the secret service management, concluding that the incident was isolated and not indicative of a broader problem within the agency.



However, the annex of the report, declassified three months ago, contains the results of a survey of 2,575 employees who identified alcohol consumption as the main kind of behaviour likely to raise a security concern.



In total, 269 employees, roughly 10% of those surveyed, were aware of "excessive alcohol consumption that causes a security concern" by colleagues.



In more than 60% of cases, an incident occurred during a mission to protect a senior government official or VIP. One in five agents who admitted to being aware of drunk colleagues, described excessive alcohol consumption as "systemic throughout the service".



Of those who had personally witnessed other agents drinking dangerous amounts of alcohol, 85% said they chose not to report the incident to a manager.



The report, produced by the Department of Homeland Security's inspector general after the debacle in Cartagena, nonetheless concluded there was no evidence that "misconduct is widespread", or found serious management failures in the secret service.



Stricter rules implemented in the aftermath of the Colombia prostitution scandal included a ban on consuming alcohol in the hotel of the protectee being guarded by the agents. A rule barring consumption of alcohol six hours prior to duty was increased to 10 hours.



In an attempt to stamp out use of prostitutes, agents are also now prohibited from bringing foreign nationals to hotel rooms where agents and officers are staying.



Three of the agents investigated over the Colombia incident later had their security clearance reinstated and are understood to have returned to duty. Five left the secret service before their case could be adjudicated, while another five had their clearance revoked because they "knowingly solicited prostitutes, demonstrated lack of candor during the investigation, or both.'