"You are aware that all pertinent records and documents available with the government have already been placed at the disposal of the JPC," the prime minister said in response to Sinha's letter.
"I have said from the beginning that neither the government nor I have anything to hide in this matter," he said.
"The decision as to what evidence should be sought and which individuals should be asked to appear before the JPC is a matter that needs to be decided internally by the JPC and its chairman," the prime minister wrote.
In a letter Monday, Sinha had asked the prime minister to appear before the Joint Parliamentary Committee (JPC) looking into the 2G spectrum allocation.
Sinha had said that former Minister A. Raja had levelled "serious allegations" against the prime minister and he should appear before the panel if he had nothing to hide.
With the prime minister having rebuffed his demand, Sinha said Wednesday that failure to do appear before the JPC would send a loud and clear signal that Manmohan Singh had something to hide.
Talking to reporters in Chennai, Sinha said if the prime minister said his conscience was clear, he should offer to appear before JPC.
"By not appearing before the JPC, the prime minister is sending a signal loud and clear that he has something to hide," he said.
Sinha also accused JPC Chairman P.C. Chako of behaving in a "partisan manner".
Chacko Wednesday rejected Sinha's demand for prime minister's appearance before the panel probing the 2G issue, saying the committee had passed that phase.
"We are now preparing the draft of the committee report for which the commitee has authorised its chairman unanimously," said Chacko, who is also a Congress spokesperson.
Chacko Tuesday rubbished Sinha's demand for calling the prime minister before the JPC as a "political stunt".
Chacko also rejected criticism for not calling Raja before the panel despite the DMK leader's insistence.
He said if Raja was called before the committee, all the telecom ministers, who served between 1998 and 2009 would have to be summoned.
Raja, an accused in the 2G spectrum case, had written to the committee last month saying the prime minister had been kept in the loop on the spectrum allocation.
The 2G spectrum was allocated by the government in 2008. According to a report of Comptroller and Auditor General, it caused a presumptive loss of Rs.1.76 lakh crore to the exchequer.
Raja and his party colleague Kanimozhi, former telecom secretary Siddhartha Behura and Raja's personal secretary R.K. Chandolia were among those arrested in the case. The accused are out on bail.
--IANS (Posted on 04-04-2013)