"Substantial evidence is already available in the public domain in the form of letters written by Singh to former telecom minister A Raja pertaining to grant of 2G licenses and action thereafter," Sinha said.
He maintained that the government had stated in an affidavit in court in the 2G spectrum case that the PM was kept informed by Raja at each step about the developments in the spectrum allocations.
On Chidambaram's role, Sinha said, "Only he can clarify why he finally abandoned the position taken by his ministry and him with regard to revision of entry fee and accepting all recommendations of Raja in a meeting with the PM on July 4, 2008," Sinha said.
"Similarly, only the PM can clarify why the policies formulated by the Cabinet on October 31, 2003 for Unified Licence were not followed up and why he allowed Raja to have his way," Sinha said, adding that no inquiry on 2G spectrum allocation would be complete without questioning Singh, Chidambaram, Raja and Dayanidhi Maran.
He described as "totally flawed and erroneous" the view that the prime minister cannot be called by the JPC.
The BJP alleged that the Congress is trying to "misuse" the JPC chairman, P C Chacko. "The message is very clear-- indulge in corruption and cover it up," Sinha alleged.
The party is also miffed at the Congress demand in the JPC to call Vajpayee and Fernandes both of whom are seriously ill.
"On July 3, 2012 the chairman was authorised to consult members and share a small list of witnesses to be called. To our utter surprise a huge list was circulated which contained even the names of Vajpayee and Fernandes. On strong protest these two names were withdrawn," Sinha said.
Finding further faults with the JPC's functioning, the BJP said it has examined only 22 witnesses in 44 sittings since March, 2011 whereas the PAC has examined 22 witnesses in 18 sittings over only eight months in the 2G spectrum case.
"The CAG was interrogated for three days by the JPC and one member was allowed not only to question him over two days but also at times humiliate him," Sinha said.
He also pointed out that the present department of telecom secretary has not been examined and the ruling party members are insisting that no more witnesses will be examined.
Sinha said he and Jaswant Singh have no issues in deposing before the JPC if the Congress wants them to. He cited the 1992 JPC example on market reforms and said he was both a witness and a member of that panel.
He clarified that he and Jaswant Singh would recuse themselves when issues relating to them are examined by the JPC. "We have no fear of appearing before the JPC," he added.