WASHINGTON: President Barack Obama on Tuesday named the first female director of the Secret Service, signaling his desire to change the culture at the male-dominated agency, which has been marred by a recent prostitution scandal.

The Secret Service, charged with protecting the president and his family, has faced intense criticism for the scandal during preparations for Obama's trip to Cartagena, Colombia, last year.

Veteran Secret Service agent Julia Pierson, who most recently served as the agency's chief of staff, will take over from Mark Sullivan, who announced his retirement last month.

She joins a notably male team around Obama, who had been criticised for bringing in several men advisers for his second term, which started in January.

''Over her 30 years of experience with the Secret Service, Julia has consistently exemplified the spirit and dedication the men and women of the service demonstrate every day,'' Obama said in a statement announcing Pierson's appointment, which does not require Senate confirmation.

The Colombia incident raised questions about the agency's culture, particularly during foreign travel. In addition to protecting the president, the Secret Service also investigates financial crimes.

Thirteen Secret Service employees were caught up in the prostitution scandal. After a night of partying in the resort city of Cartagena, the employees brought women, including prostitutes, to the hotel where they were staying. The incident became public after one agent refused to pay a prostitute and the pair argued about payment in a hotel hallway. Eight employees were forced out of the agency, and three were cleared of serious misconduct.

The incident took place before Obama arrived in Colombia, and the service said the president's safety was never compromised. But news of the scandal broke during his trip, overshadowing the summit and embarrassing the US delegation.

Sullivan issued a new code of conduct that bans employees from drinking within 10 hours of starting a shift or bringing foreign nationals back to their hotel rooms. Sullivan also apologized for the incident.

Homeland Security Secretary Janet Napolitano also praised Obama's ''historic decision'' to name Pierson as the service's first female director.

At the Secret Service, Pierson has served as deputy assistant director of the office of protective operations, assistant director of human resources and training and chief of staff. She started in 1983 as a special agent in Miami and previously worked as a police officer in Orlando, Florida.

Republican Sen. Charles Grassley of Iowa said the Secret Service has ''lost the trust of many Americans'' following the Colombia scandal. Pierson, he said on Tuesday, ''has a lot of work ahead of her to create a culture that respects the important job the agency is tasked with.''