Underlining that Ranjit Sinha's selection as the new CBI head was done in a fair and transparent manner as per Supreme Court guidelines, Mr Singh, whose tenure ends on November 30, said the idea of collegium was mooted by the agency itself.
The proposed collegium will have the Prime Minister, leader of Opposition and Chief Justice of India among others.
Mr Sinha's appointment has attracted controversy after BJP demanded to annul it contending that the Select Committee on Lokpal had suggested that such appointments should be done through a collegium method.
"This was proposed to ensure that future directors are insulated from the allegation of being the choice of the government alone, even though the present selection is as per the procedure mandated by the Supreme Court is absolutely fair and transparent," Mr Singh said.
Acknowledging that successfully putting the agency's point of view in the Lokpal debate remained one of his achievements, he said, "We are happy to note that Select Committee has endorsed this (collegium) view and I am sure that successive directors will look forward to a healthy and meaningful relationship with the Lokpal."
The outgoing director, whose two-year-long innings began with the 2G scam probe in 2010, said he had also suggested increasing the tenure of the CBI chief to five years.
"And if they cannot increase it to five years, I think it should be at least increased to three years," he said. Asserting that CBI has successfully investigated and prosecuted cases against so-called high and mighty, Mr Singh said baseless allegations of bias against the CBI and its director are totally unfounded, misconceived and unfortunate.
Mr Singh said soon after CBI completed charge sheets in the 2G spectrum allocation case, demands of bringing the agency's anti-corruption wing under the Lokpal started surfacing which would have translated into anti-corruption work taken away from the agency.
"No sooner were charge sheets filed in the 2G case, the organisation had to face the heat of the Jan Lokpal and the Lokpal Bill. In the Jan Lokpal Bill, it had been suggested that the anti-corruption wing of CBI should be merged with Lokpal while in the government Lokpal bill it was proposed that Lokpal may be given a separate agency which would in effect have meant that the CBI would no longer be involved in anti-corruption work," Mr Singh said.
He said it took lot of hard work and efforts to convince political parties and civil society groups that anti-corruption work must remain with the agency and should not be diluted in any manner.
"CBI conducts investigations in a totally free and fair manner, without fear or favour; and as per procedure established by law. CBI enjoys complete functional independence for investigation ... A high conviction rate of around 70 per cent is testimony to our professionalism and fairness," the outgoing chief said.
He said during his tenure he had always emphasised strict internal vigilance.
"Any officer or staff of the CBI must have the highest level of integrity. We have taken strict action as per rules, against any official of the CBI who was found to be indulging in corrupt activities," he said.