BS Yeddyurappa, the BJP's Karnataka chief, rubbished the allegation in a news report on Friday in the Caravan magazine claiming that he had paid Rs 1,800 crore as bribe to his party leadership. As he called the allegations "atrocious and malicious", the Congress said it could well be the first case to be investigated by India's first anti-corruption Lokpal.
The Caravan claimed to have accessed diary notings of what it said were payments by Mr Yeddyurappa to top BJP leaders and even judges. The diary entries, claims the article, were dated January 2009.
"It has been proved by Income Tax that it is, without a doubt fake. There has been a forgery of my handwriting and even my signature," Mr Yeddyurappa said.
The article claimed that the diary was found by the Income Tax department during raids in 2017 on the home of Congress leader DK Shivakumar.
As the Congress stepped up its attacks on the BJP and Mr Yeddyurappa, the government came out with a clarification.
The Central Bureau of Direct Taxes (CBDT) said the diary was found during a raid on Mr Shivakumar and a "large evidence of incriminating material" was found against him and his company.
Some "loose papers were given to the raiding party", said the CBDT.
It said they were photo copy of a Karnataka lawmaker's diary pages of 2009 with details of numerical entries against some names.
When confronted, Mr Shivakumar said it was a "copy of diary written by BS Yeddyurappa and the payments paid on behalf of Yeddyurappa to legislators, and received from various leaders, MLAs, Ministers when they were in power."
Asked how he got them, the Congress leader said he could not disclose the source. "He also stated that he did not know the time period in which the said transactions have taken place and that he did not have the originals of the said loose sheets,"the CBDT said.
Mr Shivakumar claimed he had not gone to the anti-corruption bureau of Karnataka earlier because he was not sure about the genuineness of the loose sheets.
Mr Yeddyurappa, when confronted with the loose sheets, reportedly told tax investigators that he was not in the habit of writing a dairy and that the loose sheets in question were not in his handwriting. He denied his handwriting and signatures on the loose sheets and called the entire affair an attempt to tarnish his image.
He also provided a sample of his handwriting.
The IT Dept said they asked the Central Forensic Science Laboratory to inspect the documents but it replied that no originals were given and that they cannot weigh in on the veracity of the documents.
The Caravan piece had claimed that the IT department had confirmed that the handwriting was Mr Yeddyurappa's by checking from two different sources.
The Congress tweeted: "Dear diary, it seems my corruption has been caught, I tried to bribe several BJP leaders & now the country knows. I can only hope my Chowkidar protects me like all the other Chors. Yours truly, @BSYBJP#YeddyurappaDiary (sic)."