Two civilian defense contractors have pleaded guilty in a San Diego federal court, bringing to nine the number of defendants who have admitted guilt in recent days to their involvement in a scheme involving bribes and kickbacks at Camp Pendleton and other federal facilities.

Federal prosecutors say Paul Dana Kay of PK Excavation and Manuel Ramirez of MRN Construction, Inc., entered the pleas to violations of the Anti-Kickback Act on Friday.

Six former contractors and a former Defense Department employee have pleaded guilty in the past two weeks to involvement in the scheme.

They include Natividad Lara Cervantes, who referred to himself as "The Godfather of Camp Pendleton," and admitted accepting bribes.

Sentencing is scheduled for April. The defendants face maximums ranging from three years to 20 years in prison.