The Prime Minister said the handling of high profile cases constitutes a litmus test for CBI officers.
CBI investigations should be without vendetta, witch hunt and harassment of the innocent, he said inaugurating the new headquarters of the premier agency here.
"CBI should act without fear or favour and bring all those to books who are guilty irrespective of their positions. Whoever transgresses the law of the land, however mighty, has to be brought to book," Singh said.
The Prime Minister said the CBI has set a benchmark for other investigating agencies in the country to emulate but there is room for improvement.
"Our government is committed to provide manpower, finances and technology that this premier investigating agency requires," he said.
The Prime Minister said the government has decided to establish 71 additional special courts for CBI of which 64 have been sanctioned but only 16 are operational.
Singh said over the years the CBI has evolved as the premier investigating agency of the country and there is a loud clamour for investigations to be handed over to the CBI.
He described the Rs 186 crore impressive structure as a state-of-the-art and green building.
"I am sure that this new building will provide all of you a congenial and comfortable habitat," he said.