Image copyright AFP Image caption The alleged incident happened before President Obama arrived in the Netherlands on Monday

Three US Secret Service agents tasked with protecting President Barack Obama in the Netherlands have been sent home for "disciplinary reasons".

The Washington Post reported that one was found drunk and passed out in the hallway of an Amsterdam hotel.

A Secret Service spokesman declined to give details but said the three had been put on administrative leave pending an investigation.

The service has been trying to rebuild its reputation after previous scandals.

In 2013 two agents were removed from President Obama's security detail amid allegations of sexual harassment and misconduct.

And in 2012 several agents were dismissed following allegations that they hired prostitutes while in Cartagena, Colombia.

President 'safe'

Secret Service spokesman Ed Donovan said the latest incident happened before President Obama's arrival in the Netherlands on Monday for a nuclear security summit.

He said the three had been sent home for "disciplinary reasons" but declined to elaborate.

Mr Donovan added that the president's security had not been compromised in any way.

Image copyright Reuters Image caption Secret Service agents prepare the way for Mr Obama's trips abroad and are part of his entourage

The Washington Post reported that all three were on the Counter Assault Team - which protects the president - and that one agent was a team leader.

Citing unnamed sources familiar with the incident, the newspaper said that one agent was found drunk and unconscious by hotel staff, who reported it to the US embassy.

It is believed that the other two agents were deemed complicit because they did not intervene.

On Wednesday, senior US senators on the Senate homeland security committee, which oversees the Secret Service, expressed concern about the incident.

Senator Tom Carper, chairman of the committee and a Democrat, said he had asked the agency for more information about the matter.

Republican Senator Chuck Grassley said the incident "shows that the agency has to deal with some in its ranks who fail to respect the important job the agency is tasked with".

He said newly appointed Secret Service Director Julia Pierson has "got work to do to regain the trust of the American people".

President Obama visited the Netherlands on the first leg of a weeklong, four-country trip. He departed for Brussels on Tuesday night.

The elite security force has been attempting to rebuild its reputation following the prostitution scandal revealed in April 2012.

A number of agents were dismissed after claims that they hired prostitutes in Cartagena while preparing the way for Mr Obama's visit to the Summit of the Americas.

Following the scandal, the agency put new procedures in place and officials pledged to curb its perceived male-dominated hard partying culture.

Last year, Mr Obama named Ms Pierson, a veteran agent, as the Secret Service's first female director.

And in December 2013, an inspector general's report concluded that there was no evidence of widespread misconduct within the Secret Service.