"We will hear him if he wants to continue or not. After hearing him we will pass the order," a bench comprising justices H L Dattu, S A Bobde and A M Sapre said, while posting the matter for hearing on Thursday.
The issue of Singh was raised by BJP leader Subramanium Swamy, who said that despite the apex court's May 1 order he has not been reinstated into the investigation and it was not known "what powerful element are working" that he is out of the probe.
Swamy was one of the petitioners on whose plea the 2G licences were scrapped by the apex court which is monitoring the probe by the CBI and the ED.
Senior advocate K K Venugopal, appearing for the ED, said the case was different and placed before the bench a note in which Singh expressed his desire to go on study leave.
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"Because of his option he has been released by the authority," the bench said.
However, it said since it concerns an officer it would like to hear him.
It was reported that Singh had taken a year-long 'study leave' apparently owing to lack of clarity over his continuance in the agency.
During the hearing, the bench noted that he has proceeded on leave to pursue a degree in law.
The apex court on May 1 had ordered that Singh be not taken away from the ongoing probe in 2G cases and directed that he will continue with the investigation till completion of trial.