CBI spokesperson Kanchan Prasad said the purported diary carrying several entries has been received by the agency and is being examined.
The agency had yesterday denied existence of any such entry register being maintained at the official residence of its Director.
Official sources, however, said that residence of the CBI Director also acts as his camp office where his staff sits and if something important crops up CBI officers visit that camp office.
"Last night I came across very disturbing and explosive material. The entry register of Director's residence," Bhushan, representing the NGO, had said yesterday before the Supreme Court.
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He also referred to a news report which claimed that top executives of a company indicted in 2G scam had met the CBI Director at his residence in the last 15 months.
"If you can give the copy of the material to us, CBI and Director's counsel, we can take up the matter day after tomorrow," a bench comprising Justices H L Dattu, S A Bobde and A M Sapre said.
The NGO alleged the "Director has made serious attempts to derail the investigation and prosecution being carried out by the CBI.