Saying it has "zero tolerance for misconduct in the workplace," the federal Transportation Security Administration, which oversees passenger screening at airports, is seeking to dismiss seven Philadelphia workers.

The seven are among 10 employees who were suspended in November 2011 from security duties at Philadelphia International Airport, pending an investigation into allegations of payoffs for passing grades in annual proficiency tests.

In February, training instructor Shannon Gilliam, of Sharon Hill, pleaded guilty in federal court to taking a $200 bribe from a security officer. Last week, Gilliam, 29, was sentenced to 300 hours of community service and six months of house arrest, with four years probation.

Three of the 10 employees resigned after being suspended from security duties.

The decision to fire the other seven "affirms our strong commitment to our vital security mission and the safety of the traveling public," said Chris McLaughlin, assistant administrator for the Office of Security Operations.

The investigation was conducted by the Department of Homeland Security Office of Inspector General.

Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.