NEW DELHI -- India's highest judiciary, the Supreme Court expressed its displeasure over the pace of probe into tax evasion cases related to the multi-billion-dollar telecom scam Thursday.

"The Income Tax department must be quicker. This is not a normal case of tax evasion. It (probe) should have been done fast. These are not ordinary cases to be handled in an ordinary way," a two-judge bench of the apex court said.

Though the IT department tried to defend its investigation, the Supreme Court said, "We are not concerned about layers but results. "

A number of Indian agencies are investigating the telecom scam in which the former Telecom Minister A Raja, a couple of former buraucrats, and at least five top corporate honchos have been arrested and are currently in jail facing trial for their alleged involvment in the 2G spectrum scam.

The Supreme Court is montoring the case almost on a daily basis.