Gadkari had filed a criminal defamation case on October 1 against Singh for accusing him of having business links with BJP MP Ajay Sancheti, who allegedly made Rs. 500 crore in coal block allocation.
Alleging that Singh had made defamatory statements which surfaced in the media in September, Gadkari filed the case claiming such false allegations had tarnished his image.
Outside the court, Singh told reporters that he will now prove all his charges against Gadkari.
"Now I can say everything in front of the court - the way Gadkari has worked as a businessman and how he has links with various other businessmen, which all companies of his were fake and how he earned profits," he said.
The court had also said Singh will have the opportunity to put his defence during the trial.