The Central Bureau of Investigation (CBI) has initiated a probe and summoned an employee of an auditing firm in connection with the multi-crore bitcoin scam in which senior Maharashtra politicians Supriya Sule and Nana Patole have been accused of involvement by a retired Indian Police Service (IPS) officer, media reports said.

Earlier on Wednesday, the Enforcement Directorate (ED) raided the property of Gaurav Mehta, an employee of the audit firm Sarathi Associates, in Chhattisgarh's Raipur

The CBI has registered a case against the two main accused, the late Amit Bhardwaj and his brother Ajay Bhardwaj, for running an alleged Ponzi scheme using bitcoins worth up to Rs. 6,600 crore in 2017.

The matter came to light after a retired police officer, Ravindranath Patil, accused Sharad Pawar's daughter Supriya Sule, and state Congress chief Nana Patole of being involved in a 2018 fraud case related to cryptocurrency.

The Bharatiya Janata Party (BJP) was quick to pick up the issue and said the opposition had been "exposed" a day ahead of the Maharashtra polls.

This is a major allegation against the Nationalist Congress Party (Sharad Pawar faction) and the Congress especially during the assembly elections.

The ex-cop alleged that the funds had been used for campaigning in the assembly election.

In response, Supriya Sule refuted all claims and called it the "familiar tactics of spreading false information to manipulate the righteous voters" just before the election.

The BJP, in turn, presented the media with audio clips that it claimed were evidence of the involvement of Nana Patole and Supriya Sule in what it dubbed the "bitcoin scam".

BJP spokesperson Sudhanshu Trivedi claimed the development has "unmasked" the Opposition Maha Vikas Aghadi while demanding responses from the Congress and Sule, who is a member of the Lok Sabha from Baramati.

Supriya Sule said she has launched a cybercrime complaint over such "baseless allegations" and called it appalling.

"Sudhanshu Trivedi made five allegations and asked me five questions and they (the allegations) are all false. I am happy to sit with him in any public forum -- place time and forum of his choice. it is all false and I have lodged a cybercrime complaint. i have nothing to do with any transfer of bitcoin... this shows the BJP's desperation."

Ravindranath Patil, who had taken voluntary retirement from the Indian Police Service, was employed by the Pune police along with cyber expert Pankaj Ghode to probe a couple of cryptocurrency cases registered in 2018.

The police had alleged that during investigation Patil transferred some cryptocurrencies into his account.

Ghode had provided screenshots of the accounts to police showing a lesser amount in crypto wallets.

Maharashtra voted to elect the 288-member assembly on Wednesday and the counting of votes will be held on Nov 23.