The supreme court today refused to take on record contents of a sting operation which allegedly showed that CBI pressurised witnesses in the Sohrabuddin fake encounter case to implicate former Gujarat home minister Amit Shah.

A bench of justices Aftab Alam and R M Lodha expressed reservation in considering the sting operation as a piece of evidence, noting there was enough material already before the court to decide the case.

"I have strong reservation about taking it on record," the bench said.

"Why are you bringing new materials on record. You have enough material to argue the case. These things would keep coming. If we adjourn the matter for another ten days then again new material would come out," it further said.

Senior advocate Ram Jethmalani, appearing for Shah, submitted that the sting, which was done when the politician was in jail, exposed CBI in the case.

The court, however, was not convinced and refused to take the CD of the sting operation and its transcript on record.

"In such a sensitive political matter, material would keep cropping up. If you keep on filing new materials then it would be an unending process," the bench said.

In the meantime, the bench also asked senior advocate Gopal Subramanium, who recently resigned as solicitor general, to assist it in the case.

The court was hearing a petition filed by the CBI challenging the Gujarat high court's order granting bail to 46-year-old Shah.

Shah, a close aide of Gujarat chief minister Narendra Modi, was arrested by the CBI on July 25 last and he had spend over three months in the Sabarmati jail in Ahmedabad.

Shah has been described by the CBI as the "kingpin" of the conspiracy leading to the fake encounter of Sohrabuddin Sheikh in November 2005 and killing of two key witnesses, Soharabuddin's wife Kausarbi and his close aide Tulsiram Prajapati.