Federal investigators said Thursday that the region's airports authority is afflicted by a "culture of favoritism" that led to widespread nepotism, mismanagement and questionable contracting practices at an agency overseeing the $6 billion Dulles Rail project, one of the largest public works projects in the country.

The final report from the Department of Transportation's Office of Inspector General shows that Metropolitan Washington Airports Authority senior staff picked favorites among contractors, including one firm that got a contract even though it was charging 234 percent more than some other bidders. Authority staff took lavish gifts from vendors and skirted personnel rules to get family and friends jobs, inspectors found during a yearlong investigation.

Nearly two-thirds of authority contracts worth more than $200,000 were awarded without full competition, violating the agency's own rules, investigators said. Five contracts worth $6 million were awarded with no competitive bidding at all.

"MWAA's ambiguous policies and ineffectual controls have put [the two airports and rail project] and millions of federal dollars at significant risk of fraud, waste, and abuse and have helped create a culture that prioritizes personal agendas over the best interests of the authority," the report concluded.

Authority officials said they have already started to strengthen their ethics and travel policies to correct the problems cited by investigators.

"We will use this report as a tool in expanding and enhancing our work to increase transparency, strengthen governance and build renewed public trust," authority Chairman Michael Curto said.

Authority CEO Jack Potter said some employees cited by investigators for the violations were no longer with the authority and that others have already been disciplined. He didn't offer specific numbers and didn't indicate whether additional firings or disciplinary actions would result from the investigation.

One of those blamed for the authority's problems was Arl Williams, vice president of human resources, who was cited for hiring a relative who failed a criminal background check. The authority announced Williams' retirement on Wednesday, the day before the federal report was made public.

The authority in April also fired George Ellis, its vice president for information and telecommunications services, who is cited in the report for accepting thousands of dollars worth of gifts, including Super Bowl tickets, from contractors.

Rep. Frank Wolf, R-Va., who called for the investigation, and Virginia Gov. Bob McDonnell, a critic of the agency, said the report validates concerns that they have been raising for years.

"[A] general lack of transparency and accountability, and employee misconduct have jeopardized the public's confidence in the Authority's ability to ethically manage its critical assets and complete the Dulles Rail Project," McDonnell said in a statement.

Wolf and Secretary of Transportation Ray LaHood said they would continue to push for accountability at the authority.

"The problems are very serious, and I think they have to carry out all of the recommendations," Wolf said.

NOTE: This story has been corrected to reflect that Arl Williams did not add an ineligible person to his health insurance benefits. It was a different manager in his department.