In a letter, Kumar reportedly asked the Opposition members to sort out differences with panel chairperson PC Chacko.
Opposition members of the JPC met Kumar in New Delhi on last month and submitted a memorandum where they expressed no confidence against Chacko.
Opposition members said they have lost trust in Chacko.
Fifteen members of 30-member panel submitted the memorandum to Kumar.
Several parties, including the Bharatiya Janata Party (BJP), the Janata Dal (United) and the Dravida Munnetra Kazhagam (DMK), have demanded Chacko's removal.
In one of the biggest scams of Independent India, allegedly masterminded by former telecom minister A Raja, 2G spectrum was given away at throwaway prices in 2008 causing a potential revenue loss of up to Rs 1.76 lakh crore.
Raja, who had languished in New Delhi's Tihar jail for 15 months in connection to the scam, was released on bail last year. He was arrested in 2011.
--IBNS (Posted on 02-05-2013)