A Philippine senator has filed a corruption complaint against the front runner in the country's presidential race, alleging he charged salaries for 11,000 non-existent government employees.

Senator Antonio Trillanes IV filed the complaint Thursday against Davao City Mayor Rodrigo Duterte before the Ombudsman, days after he released leaked documents purportedly showing Duterte has 2.4 billion pesos ($51 million) in undeclared wealth in various bank accounts. Duterte denies amassing ill-gotten wealth.

Thursday's complaint says ghost employee salaries in 2014 cost Davao City 708 million pesos ($15 million) and that a 2015 Commission on Audit report questioned the lack of documents to prove they were working.

The next step is for the Ombudsman to investigate the charge, and if it finds probable cause a charge will be filed before an anti-graft court.