State Department officials could not locate any documentation that Hillary Clinton and six of her top aides completed a mandatory ethics training class upon joining the administration.

According to documents unearthed by a Freedom of Information Act lawsuit filed by the Republican National Committee, Huma Abedin, then Clinton's deputy chief of staff, was pushed by State Department officials after she failed to complete an annual ethics training course in 2012.

But the agency could produce few additional records to indicate that Clinton, Abedin or other senior officials participated in a required ethics orientation or any of the mandatory annual classes in the years that followed.

The revelation, made public by the RNC Thursday, could deepen suspicion among Clinton's detractors that her tenure at the State Department was marked by a concerningly casual approach to ethics, whether that involved undisclosed foreign donations to the Clinton Foundation or an unauthorized email network on which classified information was stored.

"The State Department's own regulations say the responsibility for carrying out the agency's ethics program rests with the secretary, and by all accounts, it was never a priority for Hillary Clinton," said Reince Priebus, chairman of the RNC.

"The complete absence of records showing Clinton and her top aides completed annual ethics trainings required by federal law is par for the course for her tenure as secretary of state, where the rules didn't seem to apply and pay-to-play was the name of the game," he added.

An Office of Government Ethics report published in 2012 discovered roughly 70 percent of political appointees at the State Department failed to complete their required annual ethics training.

The RNC filed an open records lawsuit in March in pursuit of the ethics-related documents. It is one of more than a half-dozen groups presently engaged in litigation with the State Department over emails and memos from Clinton's time as the nation's chief diplomat.