"OJM secretary general Jagneswar Babu was arrested after establishment of prima facie evidence against him in loan disbursement case," SP (vigilance) S B Mishra said.
The OJM leader was produced in a court, which remanded him in judicial custody till May 4.
The vigilance department has registered cases of fraud and corruption against Jagneswar.
"I have not committed any fraud. Nabard during its verification had never pointed out any irregularity. The case against me is totally political," Jagneswar said after his arrest.
"By arresting Jagneswar, they (the government) are attempting to malign the OJM. It is a retaliation to our successful rallies across the state," he said.
While Mohapatra is number one in the OJM that vowed to oust Naveen Patnaik from power, Jagneswar has been considered as number two in the party ladder.
The anti-corruption wing of Odisha Police swung into action after getting information from NABARD regarding the fraud, Mishra said, adding that an enquiry into the matter detected serious irregularities in the loan and advances given by the officials of OSCB, Bhubaneswar to Bijayananda Co-operative Sugar Mills, Bolangir.
During enquiry by vigilance, it is found that Jagneswar, who was the president of OSCB from 2009 to 2011, illegally sanctioned and disbursed different types of credit facilities amounting to Rs 36.18 crore to Bijayananda Co-operative Sugar Mills in connivance with the Loan Committee Members of the Bank without adequate security and in blatant violation of NABARD and bank guidelines.
