The taped conversation also records the prosecution lawyer of detailing out to the accused what he has been briefing to the senior officers of CBI.

In a dramatic revelation in the 2G spectrum scandal, it has come to light that the prosecution and a prominent accused have been colluding to influence the case in Supreme Court. CNN-IBN has exclusively accessed telephonic conversations between CBI prosecutor AK Singh and Sanjay Chandra, managing director, Unitech, where Singh is heard advising the latter on methods to weaken the case against those under the scanner.

The prosecutor allegedly divulged trial strategies to the accused. Caught off guard, the CBI has transferred the prosecutor, the CNN-IBN exclusive said. The CBI believes this conversation was recorded sometime in September, 2012, days before the cross examination of key prosecution witnesses.

The taped conversation, which is in possession of the CBI, also records the prosecution lawyer of detailing out to the accused what he has been briefing to the senior officers of the agency associated with the investigation.

The CNN-IBN exclusive said that Singh at one point went to the extent of suggesting how a key prosecution witness will depose in the court and how a three-judge Supreme Court judgement could be used as a reference in the legal strategy. The investigating agency suspects that Chandra supported the prosecutor saying that a Company Law Board official would be brought in to support this stand of another witness.

The conversation then moves to Swan Telecom promoter Shahid Balwa, another co-accused. The CBI suspects prosecutor Singh is saying it is Balwa who has damaged everyone's interests in the trial and then goes on to detail how Balwa is being advised incorrectly by his legal team and other associates.

Singh as heard in the audio clips, which are attached with this story for reference for our readers, even agrees to examine defence witnesses on dates convenient to the defence. The reference to one Gaurav Jain by Chandra is also heard. Jain is believed to be the senior legal manager of Unitech.

In an interesting development, the CBI suspects their chief 2G prosecutor asking Chandra about the worth of a government lawyer like him in the market. The CBI suspects that the reply given by Chandra said that if Singh works for a corporate sector he will get a salary of Rs 3 to 4 lakh and that daily appearance rates of lawyers have doubled post the 2G scam.

The accused also enquired about the details of the chargesheet in the Vodafone case from the Singh. Chandra wanted to know if Singh was handling the case and preferred that case be filed quickly against Vodafone to reduce pressure on them.

Singh has been reportedly transferred out of the case.

Meanwhile, Unitech has denied any telephonic conversation between its managing director and the CBI prosecutor regarding the 2G case. The company said that the tapes are an attempt to malign the image of the firm and Chandra.

"The tapes may be fabricated sent by some unknown person to CBI. It is an attempt to damage Sanjay Chandra's defence in the 2G case. Sanjay Chandra never met AK Singh. Sanjay Chandra is completely cooperating with CBI," Unitech said in a statement.

Chandra also denied that it was his voice in the tapes.

Reacting to the revelation, CBI director Ranjit Sinha told CNN-IBN, "The Supreme Court, CVC and the law ministry have been informed. We are probing the voice samples."

The CBI has already filed a Preliminary Enquiry Report naming AK Singh and Sanjay Chandra on 6 February, CNN-IBN says in its exclusive.

The revelation has also shaken the political class as expected.

Chairman of the JPC on 2G scam, PC Chacko said, "The matter will be taken with the CBI director tomorrow."

In his reaction, CPM MP Gurudas Dasgupta told CNN-IBN, "This is shameful.We will take up the matter with CBI director. But i believe there are many more skeletons, this is just one of them."

The JPC on 2G scam will meet on Tuesday.

In a disclaimer, CNN-IBN said that the authenticity of the audio tapes could not be independently established.