The US Secret Service has decided to tighten its staff guidelines in an attempt to stop any repeat of the Colombia sex scandal.

Agents travelling overseas will be banned from drinking on duty, visiting “disreputable establishments” and bringing foreigners into hotel rooms.

“Consider your conduct through the lens of the past several weeks,” Director Mark Sullivan reportedly told staff.

The agency will also hold ethics sessions for staff as it attempts to move on from the Cartagena episode.

Twelve Secret Service agents and several US military officers were implicated in a night of sex and drink in the Colombian port city ahead of President Barack Obama’s visit for a regional summit earlier this month.

All 12 agents have now either resigned or are facing disciplinary action.

The US Secret Service has decided to tighten its staff guidelines in an attempt to stop any repeat of the Colombia sex scandal

The Secret Service has also said it is investigating a report that members of another advance team visited strip clubs and paid for prostitutes in El Salvador in 2011.

A spokesman said on Thursday that no “credible” evidence had been found to back up the report.

The agency described the changes as “common-sense enhancements” of existing rules – “refinements of existing rules” governing employee responsibilities and conduct.

Agents deployed on foreign assignments will in future receive briefings on arrival that include “off-limit zones and off-limit establishments”.

Drinking within 10 hours of being on duty will be banned, as will allowing foreigners into hotel rooms, with the exception of hotel staff and official counterparts. At other times only “moderate” alcohol consumption is permitted.

The 12 Secret Service agents linked to the Cartagena scandal enjoyed a night out at a well-know strip bar in the city’s port area, reported to have involved large quantities of vodka.

They later returned to the five-star Hotel Caribe accompanied by a clutch of Colombian women.

The next morning a row over payment saw one woman fly into a rage and led to the discovery of as many as 20 women in American rooms.

The Secret Service removed the men from active duty and replaced them before President Barack Obama arrived for the Summit of the Americas, insisting that the president’s safety was never compromised.

Homeland Security Secretary Janet Napolitano told Congress earlier this week that the incident in Colombia appeared to be an isolated case, saying she would be surprised if it represented a broader cultural problem.