The Chhattisgarh unit of the Congress claimed on Saturday that it has proof that "Abhishak Singh", the name revealed by International Consortium of Investigative Journalists in the Panama Papers, referred to Chief Minister Raman Singh's son Abhishek.
Abhishek Singh is a BJP Lok Sabha MP from the state's Rajnandgaon constituency.
"Ahead of changing the spelling of his name, Abhishek was allegedly the director of a company and used to spell his name as Abhishak. He had resigned from the company before contesting Lok Sabha elections in 2014," state Congress chief Bhupesh Baghel told reporters at a press conference in Raipur.
According to documents revealed by ICIJ, "Abhishak Singh" was shown to have offshore assets and the residential address mentioned in his foreign bank account was "Raman Medical Store, New Bus Stand, Ward Number 20, Vindhyawasini Ward, Kawardha," Mr Baghel said.
"Although Chief Minister Raman Singh and his son Abhishek have continuously denied knowing any person by the name Abhishak Singh, they have, at the same time, also ignored demands by the Congress to register an FIR for misusing the address of a chief minister," he said.
Abhishek Singh was allegedly the director of Chalet Estates Private Limited and used to spell his name as Abhishak, before changing the spelling of his name to the current one.
Chalet Estates Private Limited was registered in November 2011 for which the Gurgaon address of a person named Sonal Thakur was provided by the company, Mr Baghel added.
"As per the documents, initially, there were three directors - Abhishak Singh, son of Raman Singh, Aishwarya Hada, wife of Abhishak Singh and Sonal Thakur, daughter of Mahendra Kalchuri," he alleged.
He said that "Abhishak Singh" resigned from the post of director before contesting Lok Sabha polls in 2014.
The signature, of director Abhishak Singh, on Form 32, Memorandum of Association and balance sheet of Chalet Estates Private Limited and the signature on the affidavit submitted by Abhishek Singh during the 2014 Lok Sabha elections was virtually the same, Mr Baghel alleged.
Mr Baghel also alleged that a Facebook page, in the name of Abhishak Singh, was later edited as Abhishek Singh in 2014.
He demanded the resignation of the Chattisgarh chief minister as well as his MP son and said that the Enforcement Directorate should investigate the matter.
Mr Baghel accused the state government of amending the Uslapur-Mungeli-Pandaria-Kawardha-Khairagarh-Dongergarh railway project, being development jointly by the state government and the Railway Ministry, to benefit Chalet Estates Private Limited that has 17 acres of land in Ghotiya village.
Of this 17 acres, around 7 acres belong to Abhishek Singh, Mr Baghel alleged.
Refuting the charges, the Chhattisgarh CM's son termed Mr Baghel's allegations "baseless and politically motivated".
"The Congress was not getting any issues and therefore it was encouraging politics of lies," a statement issued by Abhishek Singh's office said.
Bhupesh Baghel had been allegedly involved in land encroachment in Patan area and was also embroiled in a sleaze CD case and, fearing action on these issues, he was making baseless allegations, the statement said.
"Me and my wife had transferred our shares of Chalet Estate Private Limited and its information was in public knowledge. Now I dont have any connection with this company," he said.
He claimed that the share transfer was done as per the legal provisions and there was no any violations of laws.
On allegations about the change in the spelling of his name, Singh said: "I have the name Abhishek Singh right from the start and I have never changed it. During studies, it was mistakenly written as Abhishak instead of Abhishek which was corrected by a public notice and this is in public domain.
The lands (as mentioned in the allegations) were procured by Chalet company and it does not have any connection with rail projects, he added.
"I want to reiterate that I have no foreign bank accounts. The leaders of the Congress and others had approached the Supreme Court on the issue which was rejected by the Apex Court. Bhupesh Baghel is doing cheap politics to gain mileage," he said.