A Cairo court has set a September trial date for Mohamed ElBaradei, the recently-resigned interim vice president for foreign affairs, on charges of "breaching national trust."

The charges against ElBaradei were filed by a law professor at Cairo's Helwan University, according to a report in the state-run Al-Ahram.

He stands accused of "betraying" the public by resigning on August 14, a misdemeanour charge that could carry an $1,430 fine if he is convicted.

Khaled Dawoud, a former spokesman of the National Salvation Front of which ElBaradei was one of the founders, told Al Jazeera that the prosecutor general's decision to refer the case to court was probably a consequence of the current atmosphere of polarisation in the country.

"This is a reflection of the atmosphere in Egypt right now. You cannot take your independent stand or otherwise you will be considered breaching national trust" Dawoud said.

"The complaint against ElBaradei is ridiculous. I just even could not believe this kind of case will be filed."

The longtime diplomat stepped down hours after security forces brutally dispersed two protests in support of deposed President Mohamed Morsi, killing at least 830 people, according to official figures.

In his resignation letter, ElBaradei lamented the violent crackdown, warning of a "state of polarisation and grave division... the social fabric is threatened as violence breeds violence."

According to the complaint, ElBaradei's resignation gave the wrong impression to the international community, suggesting that the Egyptian government had used excessive force against protesters. "[This] contradicts reality," the complaint said.

Under Egyptian law, anyone can file a criminal complaint, which is usually investigated by a judge who decides whether or not to refer the case to trial. In ElBaradei's case, however, because it is a misdemeanor offense, the case will proceed directly to trial; the judge will decide at the first hearing whether to allow it to proceed.

ElBaradei left Egypt for Vienna days after his resignation, and remains outside the country.