Whistleblower website Sarawak Report and a Malaysian businessman had talked about "modifying" the information contained in the PetroSaudi International documents, the source of the leaks has claimed.
Former PetroSaudi executive Xavier Andre Justo said he agreed to sell the documents he had allegedly stolen from the company to two parties for US$2 million (RM7.6 million).
"I gave the original documents without any kind of alteration," he told Singapore's Straits Times in an interview at the Bangkok Remand Prison, where he is being held while awaiting to be charged and put on trial for alleged blackmailing.
Justo claimed the people he met early this year had talked about using the documents "to try to bring down the Malaysian government", adding that they also referred to plans to "modify the documents".
"I can say that I gave those documents to two groups of people," Justo said.
According to him, the two groups were Sarawak Report editor Clare Rewcastle-Brown and "her IT guy", and the other was a Malaysian businessman and his colleague.
The names of the other individuals are being withheld by Straits Times until it is able to get comments from them.
Rewcastle-Brown, when contacted by Straits Times , vehemently denied Justo's claims.
"Why would I wish to alter anything? If I had, why haven't 1MDB and PetroSaudi brought out the evidence of such altering in all of the last five or so months?" she asked.
Rewcastle-Brown added her exposes had been backed up by Malaysian financial daily The Edge , and these corroborated with the findings of several other official sources.
The Edge , which has been accused by the government of using tampered documents in its reports on the 1MDB scandal, denied the allegation on Monday.
"We were not involved in any theft, we did not pay anyone, and we did not tamper (with) any of the e-mails and documents we were given," it said in an editorial note accompanying a four-page expose on government-owned investment fund 1MDB.
'Clean-shaven, looking well'
Justo was arrested last month by Thai police in the island resort of Koh Samui for alleged attempts to extort money from his former employer, PetroSaudi.
The Malaysian government has repeatedly claimed that documents he leaked were tampered in its bid to dismiss stunning allegations against Prime Minister Najib Razak and 1MDB involving criminal breach of trust.
According to Straits Times , Justo was "clean-shaven, looking well and composed".
"He was clad in a light blue cotton prison-issued shirt and darker blue shorts.
"Looking over his reading glasses, he showed Straits Times his confession, written densely in capital letters over 22 pages.
"He said it had not been made under duress, and that he had been pleasantly surprised at how well he had been treated in the Bangkok prison."
If found guilty, Justo faces up to seven years in jail and a fine. His lawyer, Pranot Kalanuson, told Straits Times that the Swiss national was hoping for a lighter sentence with his confession.