Replying to a PTI request for the letters under the Right to Information Act, the Prime Minister's Office cited a clause that bars disclosure of any information that "would lead to unwarranted intrusion of the privacy of the individual".
The PMO was asked to provide copies of three letters by Abraham to Singh, along with the action taken report. However, the public authority provided a copy of only one of the three letters, dated June 1, 2011, written by the former member of the Securities and Exchange Board of India (Sebi).
The others two communications -- sent on May 16 and June 24 this year -- were not provided to the applicant.
In his letter dated June 1, Abraham had alleged that some corporates and Finance Ministry officials were exploiting the vulnerability of the market regulator, which was investigating crucial cases involving prominent business houses.
"The regulatory institution is under duress and under severe attack from powerful corporate interests, operating concertedly to undermine Sebi... I believe these insidious attempts are orchestrated from the office of the Union Ministry of Finance," Abraham said in his nine-page letter.
However, the charges raised by Abraham were rejected by the Finance Ministry.
In a statement issued on August 30, the Finance Ministry had dismissed the allegations of interference in the market regulator's job as "false, vexatious and defamatory".
Replying to the request for disclosure of other two letters by Abraham, the PMO said it would invade the privacy of the former Sebi official, who retired in July this year after his three-year stint.
"...Disclosure of the said communications would lead to unwarranted intrusion of the privacy of the individual and thus, these documents attract the relevant exemptions provided under section 8 (1) (j) of the Act," the Central Public Information Officer of the PMO, Sanjukta Ray said.
The clause bars "information which relates to personal information the disclosure of which has no relationship to any public activity or interest, or which would cause unwarranted invasion of the privacy of the individual".
"The communications in questions have been received in the office in good faith/confidence from the sender and thus, the public authority and sender hold a fiduciary relationship. Therefore, this record is not disclosable under section 8 (1) (e) of the RTI Act," the PMO said in its reply.
The section exempts "information available to a person in his fiduciary relationship, unless the competent authority is satisfied that the larger public interest warrants the disclosure of such information".